CYB-132 Adds in backend code for storing and retrieving likes 

There has been no backend code for storing Likes.  This implements a simple solution.  

The front end UI to keep this as RESTful as possible, will need to know the status of a given user/gallery item, if that user has liked, disliked, or reset a previous like/dislike to neutral; or if there has been no input yet on that item from the current user.  The call from the JS UI to the code will call a different method depending on if the item already has an action.