fix stream status after adding external input success (#852)

Stream status was not set to PUBLISHER_READY causing erizo controller
not include the stream on stream list after room connection success.

erizo_controller/erizoController/erizoController.js

@@ -540,6 +540,7 @@ var listen = function () {
                                             video: options.video,
                                             data: options.data,
                                             attributes: options.attributes});
+                        st.status = PUBLISHER_READY;
                         socket.streams.push(id);
                         socket.room.streams[id] = st;
                         callback(id);