add `wordy` PHP assignment
Merge pull request #690 from wilmoore/php-wordy

wordy PHP assignment
Command + Return Submits Nitpicks See #177
Command + Return Submits Nitpicks See #177 (Missing Semi-Colons..again)
Javascript Errors, Travis Build Failed, This should Remedy it.
Merge pull request #692 from meaganewaller/command-return-submit-nitpick

Command return submit nitpick
coffee wordy assignment
Merge pull request #693 from wilmoore/wordy-coffeescript

Wordy coffeescript assignment
CoffeeScript "Binary Search Tree" assignment
Merge pull request #695 from wilmoore/coffee-bst

CoffeeScript "Binary Search Tree" assignment
Auto-start trails. Fixes #687.

This gets rid of the notion of starting trails explicitly. If you submit
an exercise on a trail that you don't have a current exercise for, then
that exercise becomes current.