[bluetooth] complete basic bluetooth music funcs.

1. complete functions following: search, pair, connect, a2dp, play,
pause, previous song, next song, fast forward, fast backward.
2. require for UI optimizing logic simplifying.
3. there may be some bugs, which don't take influence on other modules.
4. BUG: our app is confict with bt phone, which share a common bt
service with our app. anyone know why? It's very kind of you to tell me.
Merge branch 'master' of github.com:2014-1/001