Support for LG Optimus 4X P880

This patch adds support for the default music player included with LG Optimus 4X P880, and perhaps other LG devices (I saw some open issues on other devices).

The patch seems to work, although I couldn't see my tracks being scrobbled to last.fm, only the "listening playing" message (I guess the API key is missing). libre.fm scrobbling works just fine.

At first, I tried to get it working with the BuiltInMusicAppReceiver, but got a "no such media in media store" exception. Eventually I went with a separate class.

Keep up the good work with this app :-)
Shahar