XBMC metadata update

This PR adds several items to the nfo generated for XBMC:
- MPAA + outline, by fixing a bug
- Actors with full info
- Trailer if available
- Posters and backdrop
- Stream info (e.g. codec, aspect ratio, etc.)
- Adds option to do a full scan (notification)

Note that this PR has not been tested fully yet and currently breaks down. Reason being that actors is adjusted, but couchpotato API is not adjusted yet. See comments in the code below.

Fixes #783, #1412 and #2498