bug: keep-alive timer only starts if an operation request is sent

SDK version: 4.0.0.2
description:
If a client app does not explicitly send an operation request after connecting to the server, the keep-alive timer does not start. Consequently, the client will be disconnected from the server after the timeout expires.

fix:

# from photon.js:444
PhotonPeer.prototype._onConnect = function () {
  this._logger.debug('PhotonPeer[_onConnect] - Connected successfully! Raising "connect" event ...');
  this._isConnecting = false;
  this._isConnected = true;
  this._dispatchPeerStatus(PhotonPeer.StatusCodes.connect);
  this.resetKeepAlive(); # add this line
};