More entries.
Added:
 plex_duration - duration of media in seconds, as requested in #2357
 plex_episode_thumb - url for episode thumbnail.
 plex_series_art - url for series cover art.
 plex_season_cover - url for season thumbnail.
 plex_episode_title - episode title as indexed.
 plex_episode_summary - episode sumamry as indexed.
 plex_url - original url to media.
Merge branch 'planeturban'

Conflicts:
	flexget/plugins/input/plex.py
Merge branch 'master' of https://github.com/Flexget/Flexget
Cleanup of plex.py.
Fixed merge errors.