Support for more audio formats

Only 16-bit WAV files or lower are currently supported. I'm hoping in the future that XULRunner/Firefox will support more formats for the &lt;audio&gt; element (see <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=524109">bug 524109</a>), as that would be the easiest fix. If not, other solutions may eventually be considered.
