Add WAV files for testing audio playback
Moved test WAV files from assets to res/raw folder
Trying out SoundPool

There seems to be less delay between pressing the button and hearing the
sound. There's still a noticeable delay when stopping and then replaying
the sound.
Move playback logic to PlayState class
Refactor PlayState

Converted audioManager to instance field initialized in PlayState's
constructor.
Merge PlayState changes

Conflicts:
	src/com/panzoid/soundboard/controller/MainActivity.java
	src/com/panzoid/soundboard/model/state/PlayState.java
Modified test sound files

Removed the small duration of silence at the beginning of each sound
file.
Merge pull request #1 from cg50x/master

Playback with SoundPool