Server-side status is mostly working.
Fixes

* Volume wasn't working on mobile Chrome because the mouseup event
  wasn't always occurring. Changed the event to onChange and throttled
  the rate they can be sent to the server
* Fixed bug where when a browser connected the offset in the song was
  not set correctly
* On song completion the metainformation gets set to empty.
Fixed Seeking

Changed the seek widget events from mouseup to changed so that
seeking works on Chrome mobile. Also throttle sending seek requests
to the server, and wait for a seek event matching our seek request's
offset before updating the position widget to prevent it from jumping
around after setting position.