As default music player

You can not select foobar2000 as default music player. When connecting to bluetooth device foobar2000 can not open automatically, so default music app opens and start playing.

- add foobar2000 to music app list in android
- start foobar2000 on android play command
- remove or fix headphone buttons support, since it does not work. android will do it for you.
- search and play track in playing now, currently search only works for whole library and will play only one track
- a way to go back to playing now, to change track