[tmdb] Completed themoviedb.py scraper module

* Emit dc.date and dc.type (genre)
* Fix configuration api url
* Replace title derived from filename (only emit tmdb title)
* Fixed poster being used as fanart instead of backdrop
* Cosmetic: use of both "http://themoviedb.org" and tmdb_base variable has been made consistent (only url now)
* Use CachedSimpleResource for configuration api call