Change subtask format to include subtasks in markdown.

Subtasks no longer need to be included in yaml, or require a filter.

See an example athttp://github.com/shmck/coderoad-tutorial-subtask-demo

###1.1A description of the task####SUBTASKS- The first subtask- The second subtask

Subtasks are then matched up with tests with names that match

SUBTASK 1.1 :1 test nameSUBTASK 1.2 :2 test name

UI redesign for the tutorial page:

• removes unnecessary headers
• adds a side panel
• step progress indicator
• removes logs from error messges

Supports "reset button" for resetting state & running a reset script.

Adds a review page for viewing tutorial content. The review page should be especially helpful for tutorial creators.