Add trait for recommended feed items
Enable scopes that can check controller params

By passing in self when we execute the scopes, we can use scopes that
scopes the feed items based on controller params.
Update readme to reflect changes in filtering
Refactor how we can pass parameters into scopes
Remove instance eval and configurable scopes
Merge pull request #15 from hyperoslo/feature/parameters-in-scopes

Enable the use of parameters in scopes