message: When joining, use a roomAlias if we have it
  And default to the current roomId otherwise
diff: @@ -137,7 +137,9 @@ class RoomViewStore extends Store {
  this._setState({
  joining: true,
  });
  - MatrixClientPeg.get().joinRoom(this._state.roomId, payload.opts).done(() => {
  + MatrixClientPeg.get().joinRoom(
  + this._state.roomAlias || this._state.roomId, payload.opts,
  + ).done(() => {
  dis.dispatch({
  action: 'joined_room',
  });
  