Make tags a first class citizen

[scytherswings]

We should have a concept of taggables.
A tag is in actuality a key which is unique
tags have_many values, which are also unique in the scope of the tag's key
tag values will be json possibly so we can have more advanced structures, though a string might suffice.

So here's the commands to generate this structure in pesudocode.

rails g scaffold tag key:string
rails g model taggable_tag tag:references taggable:references{polymorphic}

[scytherswings]

https://github.com/mbleigh/acts-as-taggable-on