IDEA: Provide a TMDb plugin

[Simón Pena Placer <spenap gmail com>]

The Movie Database (TMDb) [1] is a "free and open movie database".
It's currently used in many popular media centers like Moovida, XBMC,
Plex, MythTV and MediaPortal and provides an API to access different
movie info, like overview, rating, poster images and more,

It would be nice to have a MetadataSource plugin for it, so you can
retrieve information about a given movie.

[1] http://www.themoviedb.org/