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.
Unused method argument - `row`. If it's necessary, use `_` or `_row` as an argument name to indicate that it won't be used. You can also write as `create_or_update_from_csv_row(*)` if you want the method to accept any arguments but don't care about them.<br>Unused method argument - `assignment`. If it's necessary, use `_` or `_assignment` as an argument name to indicate that it won't be used. You can also write as `create_or_update_from_csv_row(*)` if you want the method to accept any arguments but don't care about them.