Updated the XAudioJS test page with a demo visualizer

http://www.grantgalitz.org/sound_test/ now plays a WAV file by decoding it
from base 64, then decoding the WAV data and streaming it through the
library. I made a visualizer to show that it indeed is streaming the
samples in real time. I hope you all enjoy it. :D

Also, it takes about 45 seconds for it to start, as it has to ajax in a WAV
file (See above).