Testing fix

Likes being inserted as hashes breaking "liked?" method  Attempting to resolve
Previous Mongoid 4 fix broke "Liked? function because was pushing/pulling hash instead of just object _id.  Corrected the issue here.
Pull not valid BSON method - changed to delete in Unlike Method
Merge pull request #2 from dorthwein/master

Previous pull broke Liked? method because was inserting a hash instead of just the object ID