Adding 'likes' to the database
Resolved merge conflicts from updated schema.db
Updating user and likes model to implement association
Added 'matches' method to user model to calulate mutual 'likes'
Moving match rate method to the mixtape model
Merging with latest develop
Updated likes controller to 'find_or_create' for 'create' action
Setting default gender value to be opposite to user's own
User's can block and like another user