Add stereo support

[afraser]

Addresses #1

Note: This needs further confirmation. While this appears to work from a technical standpoint, manual testing against songs with heavy stereo panning is disappointing. I assume the issue has to do with compression in one way or another.

Manual testing note (single machine):

• Find a track with heavy stereo panning (eg: Whole Lotta Love by Led Zepplin has some crazy panning about 1/3 a way into the song)
• Play the song on a tab ("Source Tab") in the browser
• Mute that tab via right click "mute this tab"
• Open a new tab ("Host Tab") to the JamLink client app and create a host to stream that tab.
• Open a 3rd tab ("Client Tab") pointed to the JamLink room and play it.
• You can now compare this audio to the source audio by unmuting the Source Tab and turning the volume down all the way on the Client Tab.