Correcting to make RFC3003 compliant so Chrome works

L714 correct codec: 'audio/mpeg; codecs="mp3"', to codec: 'audio/mpeg'

Tested in Chrome, Firefox and IE - all works.

See https://code.google.com/p/chromium/issues/detail?id=386073 and http://tools.ietf.org/html/rfc3003