Add ability to specify which library gets updated in manual sync with a new variable, library.

Add ability to specify which library gets updated in manual sync with a new variable, library. This still checks if episode/movie sync is enabled or disabled.
Usage: RunScript(script.trakt,action=sync[,silent=True][,library=[all|episodes|movies]])
The variable is optional, and if omitted defaults to all.
Merge pull request #155 from nate1280/manual_sync_changes

Ability to specify which library is updated in manual sync.