Audio.js: jaws.Audio and its unit tests

Changes:
-- jaws.Audio! 

Finally, the introduction of an official jaws.Audio object that uses jaws.assets to detect and load supported audio file formats. (Currently checks for WAV, OGG, MP3, AAC, MKA, WEBA, and FLAC support.)

-- Addition of tones{aac, flac, mka, mp3, ogg, wav} in test/assets for testing Audio object in most modern browsers.

-- Preliminary unit tests for audio.js.

-- Commented out testing for text.js and quadtree.js in test/index.html (new versions and testing to follow soon)