Fixes issue#52. Notes:

• The fix applies to bothtypeis andtypeis.is, instead of justtypeis.

  This is becausetypeis.is can receive a req-like or res-like object (this behaviour is undocumented buttested). I wanted to avoid situations wheretypeis(req, ...) would work buttypeis.is(req, ...) would not.

• The fix breaks backward compatibility in that, previously,typeis would fail if the content-type parameters were not properly formatted. But, after this PR, it will just ignore them.

  i.e. previously, this would returnfalse:

  typeis.is('application/json; charset:utf-8', 'json') // Notice the ":" instead of "=" in charset

  But after this PR, it will return"json".

  This behaviour was documented (...If theContent-Type header is invalid...):

  type-is/README.md

  Lines 35 to 38 in7d19b7a

  	Checks if the`request` is one of the`types`. If the request has no body,
  	even if there is a`Content-Type` header, then`null` is returned. If the
  	`Content-Type` header is invalid or does not matches any of the`types`, then
  	`false` is returned. Otherwise, a string of the type that matched is returned.

  But it was not tested in the case of invalid parameters. I am not sure of the best way forward:

  • Keep validating parameters, and make test cases for it,
  • Or update the documentation to clarify that parameters will not be validated.

• After this PR,media-typer dependency could be upgraded to 1.1.0.