Could we have controller helpers?

[seancdavis]

Kind of building off #73, what if we have a class that sits between ApplicationController and a specific controller (or maybe even below ApplicationController), such that there are some added benefits to be DRY.

For example, we could have a model set that would become our model of interest for the class. And some keywords like scope could call a method that would know what to do.

Probably overkill, but something to think about.