Handle errors on "decodeAudioData"

In Safari and Firefox (OS X) I encountered an issue with audio that loaded, but failed to decode. Currently JAM does not handle or surface this error. Ideally it would console.error, or dispatch an event.

[Here is a file that failed](http://playpen.createjs.com/samples/bensound-funkysuspense.mp3). It is 44kbps. When it was re-encoded for 48kbps, it worked fine, so that _could_ be the cause. The error happens specifically when the file is loaded in an iframe, and it seemed to work fine when loaded in its own window.