iOS NativeDemo: Use external speaker

[stefanalund]

Possibly switch to "internal" speaker when phone is hold by the ear.

[superdump]

Something to do with this: https://developer.apple.com/library/ios/documentation/AudioToolbox/Reference/AudioSessionServicesReference/index.html#//apple_ref/doc/constant_group/Audio_Session_Category_Route_Overrides but the osxaudiosink element has a device property that most likely can be used to switch to the speaker and back. There are rules for how these behave when you connect a headset too.

Side note: when putting the phone up to your ear, it would be nice if the screen went black and became unresponsive like the Apple Phone stuff does.