Split apart movie operations during sync

Movie operations during sync have been split into 50 item chunks now, seems initial syncs or large syncs were causing 500 Internal Errors at trakt.tv, this must be a recent change, as it use to be fine.

Split apart the adding of movies to trakt
Split apart removing of movies to trakt
Split apart updating movies to trakt
Seems recently it has not been working (500 internal error) if there is a large amount (400+ in adding, 120+ in removing)