Allowing for auto-application of scopes

I extracted some code I’ve used in a few projects into a gem that plugs into ActiveRecord and thought that it might be useful as a core feature.

Basically, it allows you to apply scopes from parameters by keeping a meta-definition of what your ActiveRecord scopes are. Implementation could be improved, but it is pretty useful, cleans up tons of controller code and I didn’t see anything else like it when I searched around.

Hoping to get some feedback on whether it would make sense to submit a pull request.