enter_room and leave_room don't work

[Roxe322]

Hello! In #20 you added ability to join and leave rooms, but you made it as properties so when you call
sio.enter_room(sid, room)

it results to

TypeError: enter_room() missing 2 required positional arguments: 'sid' and 'room'

It should be not properties but methods.

[Roxe322]

Otherwise, it could be just proxy-properties, without any params:

    @property
    def enter_room(self):
        return self._sio.enter_room

    @property
    def leave_room(self):
        return self._sio.leave_room

[Roxe322]

So I made a pull request: #25