OpenSubtitles API to get subtitles working with torrents

- Usage of MPAA to save IMDB code to better search subtitles in opensubtitles API;
- Similar code used in Genesis addon of @lambda81;
- Possibility of search for primary language or secondary language (in case of first doesn't have any results).

Similar setup on XBMCtorrent fork I was maintaining almost "privately" to me:
https://github.com/Mafarricos/Mafarricos-modded-xbmc-addons/tree/master/plugin.video.xbmctorrentV2