AudioAttributes for SoundPool

Add support for building a SoundPool instance and specify
 the AudioAttributes.
Remove SRC quality which was never implemented, while leaving
 room for supporting it later through the Builder pattern.
Remove stream types.
Update AudioService's use of SoundPool to the new scheme.

Change-Id: Ie51e4008684e5ba25f9b7368098e4f20266a15c7