Don't start playing if we couldn't acquire audio focus.

This makes us not start playback when we get a 'play' media button event
in the middle of a call for whatever reason.

JIRA:CYAN-1067
Change-Id: If648da95c10716400eeba0b39a24213764370f7a
Fix audio session ID handling when invoking DSP manager.

Change-Id: I8ebb71e32191b79f08cfa9c72fab311048992fe8
Merge "Don't start playing if we couldn't acquire audio focus." into cm-10.1
Make sure notification is shown when playback is started via media
button intent.

Also make sure to properly remove it when music is stopped with screen
of (e.g. when playing via BT): As handlers only count non-sleep times,
we have to use the alarm manager in order to make sure the notification
is removed after 1 minute.

JIRA: CYAN-1067
Change-Id: I87a5328e5116d199e2f62119f5a76eca73a3ee4e
Merge "Make sure notification is shown when playback is started via media button intent." into cm-10.1
Fix merge derp.

Change-Id: I073afea4845958d0691687771c681c2e0900053e