5060 fifty most popular tags

This is currently using an edited version of the 'acts-as-taggable-gem' that I have tweaked to include a 'most_used' & 'least_used' feature and is hosted on the wegotcoders github page. Both of these features have been ok'd by the act-as-taggable team and are just waiting to be merged into the main gem.
We already have a db/schema.rb and this PR includes no migrations, so please remove this from the commits.