message: Dispatch incoming_call synchronously
  this should fix a race where if the 'hangup' arrives hard on the tail of the
  Call.incoming, we don't ignore it.
  (We still have a problem in that we blip the hangup tone and UI, but that is
  arguably a separate problem)
diff: @@ -1068,10 +1068,13 @@ module.exports = React.createClass({
  self.setState({ready: true});
  });
  cli.on('Call.incoming', function(call) {
  + // we dispatch this synchronously to make sure that the event
  + // handlers on the call are set up immediately (so that if
  + // we get an immediate hangup, we don't get a stuck call)
  dis.dispatch({
  action: 'incoming_call',
  call: call,
  - });
  + }, true);
  });
  cli.on('Session.logged_out', function(call) {
  const ErrorDialog = sdk.getComponent("dialogs.ErrorDialog");
  