Linking Tag Controller to Tag Views

This pull request contains changes that link the Tag Controller to Tag Views. Currently the following features have been implemented:
* Tag table in Views/Tags/index.html.erb is now partially working (more work needs to be done on the tag links.
* Modifications have been made to the Tag controller to support creation, deletion and grouping features.
* A Tag helper has been created to allow for Ajax querying of the ActiveRecord.

Currently, not much testing has been done. This is currently a work in progress.
@david-yz-liu  Whoops, totally missed this. I don't think I ever made classes like this, but it would make sense to put them in `common/_core.scss`, especially if you intend on using them more later.

Side note: it might make sense to take the `color` property and put it somewhere else, since I doubt everything that you can use the `alignright` class for would necessarily have grey text.