[airplay] - implement different announcements when using the ios8 compatibility mode
[settings] - add new expert setting for enabling ios8 compatibility
[airplay] - implemented photo asset cache

Conflicts:
	xbmc/network/AirPlayServer.cpp

Signed-off-by: Jérôme Benoit <jerome.benoit@piment-noir.org>
[airplay] - send an error code for the fp-setup request
[airplay] - add some handy helpers for using binary plists

Conflicts:
	xbmc/network/AirPlayServer.cpp

Signed-off-by: Jérôme Benoit <jerome.benoit@piment-noir.org>
[airplay] - handle /play of newer airplay protocols - instead of location it sends 2 seperate entries host + path
[airplay] - merge the binary plist and xml plist pathes in airplay (which already diverged) by using libplist for parsing in both cases - not only the binary case
[airplay] - support the /play command which wants us to start playback "paused" - (camera roll on ios8 for example)
[airplay] Don't be overzealous on the IOS8 support backport.

Signed-off-by: Jérôme Benoit <jerome.benoit@piment-noir.org>