Hide button if no streams found
Reinit cuepoints on mediachange

Change media causes kCuePoints to be destroyed - so must be initialised
again
Add strat/finish events for stream change
Add actions on media/stream change
Add sync flag for slides
Freeze slides/chapter time on stream change
Add entry id data to changeStream event
Merge pull request #1258 from kaltura/streamSelectorFix

Stream selector fix