We used to have our own WebSocket wrapper, which was replaced in
cf410d0bd2127973739208ef94b2df59cc0b720e with angular-websocket,
since that provided the functionality that we needed on top
of WebSockets, namely:

 * Integration with Angular $scope by wrapping onmessage callbacks
   with $scope.$apply()

 * Automatic reconnection in the event of a disconnection

 * Queuing of messages sent prior to a connection being established.

Unfortunately, angular-websocket also brings in a somewhat unnecessary
dependency on the "ws" module. That got out of date and resulted in no longer
being able to build H with the current version of Node.
See https://github.com/AngularClass/angular-websocket/issues/47

This gave us either the choice of fixing angular-websocket or
replacing the dependency.

This commit removes the angular-websocket dependency in favor of
our own WebSocket wrapper, but unlike before, we outsource the retry logic
to the "retry" package. A benefit of this is that we get better logging
of what is going on during automated reconnects.