Finalized 'Add Topic' form, and added validations for same

-Made the add topic form fully AJAX-y
-Added basic presence validations (activerecord) to topics
-Added validation messages on add topic form
-Did some light styling on form to make it look pretty
Adding some comments to my javascript
Merge pull request #7 from jcerise/master

Finalized 'Add Topic' form, and added validations for same