Feature/howler audio

#157 

I think i updated all the necessary methods and so forth. Two things of note, since we no longer manage channels, i just have the sound_id in the audioTracks hash simply store the howl object. Channel has been removed from documentation.

The second thing is that Howler does not seem to have a streaming option. I did a search on here: http://goldfirestudios.com/blog/104/howler.js-Modern-Web-Audio-Javascript-Library he responds in the comments that it exists, but given how our code supported it with `canplay` event, I just see in the howler code `canplayThrough` events being registered.