Add rotten tomatoes, imdb, metacritic ratings

[DragonzMaster]

Hi, First, thanks for this project. Want to ask if there any chance to add more ratings (may be from rotten-tomatoes or IMDB or meta-critic). I know there is a plan to migrate from trakt.tv to themoviedb.com so it would be nice if you could add another ratings in the future.

[amilajack]

This might take some work. I'm somewhat reluctant to add support for a specific service. All the services that this project uses have some kind of provider architecture, which means that services can easily be swapped with each other. So I or other users will need to create something like a RatingsAdapter, and create a provider for rotten tomatoes, imdb, and other possible endpoints. I'm somewhat worried about the complexity that this will bring to the project and how much time it would take to add this functionality. But its still possible.