Added comment model spec.
Added username validation to User.
Added Tag model tests, validation to tag_text.
Changed tag_text to be a string instead of text.
Altered username and tag_text regex to accept hyphens as well.
Simplified tagging functionality, added tests for it.
Added Tags Controller tests.
Simplified tags controller code, made it accessible by tag text.
Made test code clearer.
Merge pull request #41 from maxluzuriaga/master

Username/tags validation, tags controller changes, many many tests.