GPII-398: Adding get/set wrapper for Android's Stream Volumes

This bridge provides the ability to deal with Android's stream volumes
such as STREAM_VOICE_CALL, STREAM_ALARM, STREAM_SYSTEM, STREAM_RING,
STREAM_NOTIFICATION, STREAM_DTMF and STREAM_MUSIC, by using both
getStreamVolume and setStreamVolume native methods.

All these settings are set in the same way, and are well described here.
http://developer.android.com/reference/android/media/AudioManager.html

Since this is a just a small part of Android's AudioManager API, this
module could be improved to cover more features from the same API.
GPII-398: Add the new source code into the build system

* Adding the code into ant.properties in order to be built
* Adding the new line into makestubs.sh in order to generate the new
stub
GPII-398: Adding a settings handler for Android's audioManager

Adding both getVolume and setVolume javascript methods.
GPII-398: Always use an integer type when setting volumes
GPII-398: Re-indent with spaces instead of tabs
GPII-398: Splitting audioManager into its own node module

* Adding node_modules/audioManager
* Removing the code for audioManager from activity_manager.js
* Updating gpii.js accordingly
GPII-398: Putting the right copyright in index.js file
Merge remote-tracking branch 'javihernandez/GPII-398'

Conflicts:
	gpii.js
	platform/app/ant.properties
	platform/makestubs.sh