[android] Initial Android TV support

This simply means adding an entry to the TV launcher. The launcher seems to have natively wide non-square icons, but it seems to use our existing icon just fine, showing "XBMC" in the remaining space of the icon.

This adds no other integration. Tested on ADT-1 Android TV device.

Video playback seems to work fine, audio playbacks work with stereo
PCM and basic passthrough. PR #5082 adds 5.1 PCM support.

There are two significant issues that I saw:

- crash on exit, looks like double free at /system/lib/libmedia.so
  (android::sp<android::AudioTrackClientProxy>::~sp()+10),
  maybe something to do with threading? or just an Android bug...
Full log here: http://onse.fi/files/adt-xbmc-exit-crash.txt

- a warning flood on playback of many videos:
  W/art: Attempt to remove local handle scope entry from IRT, ignoring

Both of these look like either general issues introduced with Android L
and/or ART, not Android TV specific issues (but I did not confirm that).

Has anyone tried XBMC on ART and/or on the Android L preview? If so, did one/both of these issues exist there as well?