Add Filesystem component documentation

Commits-------a20fc68 Merge pull requestsymfony#1 from SamsonIT/FilesystemExceptions8eca661 [FileSystem] explains possible failure of symlink creation in windowsb1f8744 Add Changelog BC Break note24eb396 [Filesystem] Added few new behaviors:Discussion----------[Filesystem] Consistence and enhancements for FilesystemBug fix: noFeature addition: yesBackwards compatibility break: **yes**Symfony2 tests pass: yesFixes the following tickets: NoneLicense of the code: MITThis PR adds features and introduce a backward compatibility break.features :- whenever an action fails, a \RuntimeException is thrown- add access to the second and third arguments of ``touch`` function- add a recursive option for chmod- add a chown method- add a chgrp methodThe backward compatibility break happens in the mkdir method : Before this PR, a boolean is returned ; true if all directories were created, false otherwise.It now returns nothing.---------------------------------------------------------------------------by travisbot at 2012-05-18T14:26:42ZThis pull request [passes](http://travis-ci.org/symfony/symfony/builds/1367000) (merged 83cdd622 into1e15f21).---------------------------------------------------------------------------by fabpot at 2012-05-20T02:40:28ZTo be consistent, we should throw exception whenever some operation fails.---------------------------------------------------------------------------by romainneutron at 2012-05-20T21:10:23ZI fix the consistency ; mkdir now throws an exception if a directory creation fails.This introduce a BC break, see PR message which has been updated with all features and BC break.Added chgrp and chown methodsAdd options for touchAdd recursive option for chmod---------------------------------------------------------------------------by travisbot at 2012-05-20T21:11:47ZThis pull request [passes](http://travis-ci.org/symfony/symfony/builds/1383619) (merged a4d1eeb8 into1407f11).---------------------------------------------------------------------------by travisbot at 2012-05-22T10:49:06ZThis pull request [passes](http://travis-ci.org/symfony/symfony/builds/1399027) (merged 7e14b6bd into517ae43).---------------------------------------------------------------------------by travisbot at 2012-05-22T10:58:10ZThis pull request [passes](http://travis-ci.org/symfony/symfony/builds/1399083) (merged 71852653 into517ae43).---------------------------------------------------------------------------by travisbot at 2012-05-22T11:18:44ZThis pull request [passes](http://travis-ci.org/symfony/symfony/builds/1399194) (merged 7645bad3 into517ae43).---------------------------------------------------------------------------by travisbot at 2012-05-23T18:21:47ZThis pull request [fails](http://travis-ci.org/symfony/symfony/builds/1414091) (merged b049d5b1 into517ae43).---------------------------------------------------------------------------by travisbot at 2012-05-23T18:26:19ZThis pull request [fails](http://travis-ci.org/symfony/symfony/builds/1414123) (merged 34903466 into517ae43).---------------------------------------------------------------------------by travisbot at 2012-05-29T16:07:26ZThis pull request [passes](http://travis-ci.org/symfony/symfony/builds/1467173) (merged b1d1eb2e intoadf07f1).---------------------------------------------------------------------------by travisbot at 2012-05-29T16:19:38ZThis pull request [passes](http://travis-ci.org/symfony/symfony/builds/1467261) (merged 42015ffa intoadf07f1).---------------------------------------------------------------------------by romainneutron at 2012-06-01T14:30:45ZAny news about this PR ?---------------------------------------------------------------------------by stloyd at 2012-06-08T09:57:39Z@romainneutron You need to [squash](http://www.silverwareconsulting.com/index.cfm/2010/6/6/Using-Git-Rebase-to-Squash-Commits) your commits, and add more proper message in squashed commit i.e.:> [Filesystem]  Added few new behaviors:* whenever an action fails, a `RuntimeException` is thrown* add access to the second and third arguments of `touch()` function* add a recursive option for `chmod()`* add a `chown()` method* add a `chgrp()` method> BC break: `mkdir()` function throw exception in case of failture instead of returning Boolean value.---------------------------------------------------------------------------by romainneutron at 2012-06-08T10:59:55Z@stloyd squash done !---------------------------------------------------------------------------by travisbot at 2012-06-08T11:26:20ZThis pull request [passes](http://travis-ci.org/symfony/symfony/builds/1565540) (merged 8f55ddb6 intof8e68e5).---------------------------------------------------------------------------by travisbot at 2012-06-08T11:41:45ZThis pull request [passes](http://travis-ci.org/symfony/symfony/builds/1566247) (merged 880312b6 intof8e68e5).---------------------------------------------------------------------------by romainneutron at 2012-06-09T11:42:24ZI've added documentation to the Filesystem component :symfony/symfony-docs#1439---------------------------------------------------------------------------by travisbot at 2012-06-09T16:47:20ZThis pull request [passes](http://travis-ci.org/symfony/symfony/builds/1577754) (merged 5647ad41 intof8a09db).---------------------------------------------------------------------------by stloyd at 2012-06-13T14:47:31Z@romainneutron You probably need to rebase your code as some changes were merge into master for `Filesystem`.---------------------------------------------------------------------------by romainneutron at 2012-06-13T15:17:31Z@stloyd rebase OK !by the way, do you have any idea when/if this PR will be merged ?---------------------------------------------------------------------------by travisbot at 2012-06-13T15:20:44ZThis pull request [passes](http://travis-ci.org/symfony/symfony/builds/1611591) (merged c8b86c68 intoc07e916).---------------------------------------------------------------------------by fabpot at 2012-06-16T16:40:50ZYou need to add a note about the BC breaks in the CHANGELOG file.---------------------------------------------------------------------------by fabpot at 2012-06-16T16:43:20ZAlso, instead of using `\RuntimeException`, I would create a custom exception like we have done in other components (an interface + a RuntimeException that implements the interface and extends \RuntimeException). The exception name can be something like `IOException`.---------------------------------------------------------------------------by travisbot at 2012-06-18T10:11:20ZThis pull request [fails](http://travis-ci.org/symfony/symfony/builds/1645757) (merged 925a8234 into0b8b76b).---------------------------------------------------------------------------by stloyd at 2012-06-18T10:14:52Z@fabpot Anything blocking merge of this PR ? (tests are failing because of issue in master, not releted to this PR)---------------------------------------------------------------------------by romainneutron at 2012-06-18T10:29:20Z@fabpot@stloyd the latest push was just a rebase push for PR 4577 (symfony#4577)I'm currently fixing the Exception and changelog things, I'll push very soon---------------------------------------------------------------------------by romainneutron at 2012-06-18T10:44:38Z@fabpot I've added the exception and the exception interface, add the changelog info---------------------------------------------------------------------------by travisbot at 2012-06-18T10:53:34ZThis pull request [fails](http://travis-ci.org/symfony/symfony/builds/1645981) (merged 634d6fb9 into0b8b76b).---------------------------------------------------------------------------by romainneutron at 2012-06-18T11:08:43ZAs reported by@stloyd the PR is failing due to an issue in the master, I re-push and trig the PR build when this issue is solved---------------------------------------------------------------------------by travisbot at 2012-06-18T11:16:58ZThis pull request [fails](http://travis-ci.org/symfony/symfony/builds/1646006) (merged 2f65945a into0b8b76b).