Make AirPlay photo sharing works with iOS 7.1

(cherry picked from commit dc99ee7ca11f6dad18a93a4ab959ca4cae16ffd2)
No need to add randomisation to bonjour first registration

(cherry picked from commit bdc75ddcec79e631149d3d42d373694c0fb1ca7b)
Improve AirPlay photosharing

Make the AirPlay photo sharing’s behavior closer to what an Apple TV does:
- Make the photo disappear whenever you exit the photo application
- Allows to play music while showing photos
- Improve transition between photos and videos
- Only make the photo disappear once video playback has started

(cherry picked from commit 9cba5e278763bb6d18603cf9f916ef7c75157953)