Bugfix/postroll restarts

This fixes a bug where we had combined the conditions of player.ended() and the src unchanged, such that we were falling into an else condition which called player.load() whenever player.ended() returned true.
Its not expected that client-side ad implementations will be sending ended events to the content player.  I am fine with reverting this particular part of the fix if you want though as it is unrelated to the more important problem of falling into the else condition above.