Adds `connect_callback`, `disconnect_callback` parameters and `item_callbacks` property to C4Websocket.
1.0.0b5
Breaking changes for C4Websocket - renamed "device" functions to "item" to better reflect that Control4 item IDs are being passed in - director_bearer_token is now passed into sio_connect(), to allow token refreshes without re-init C4Websocket - added sio_disconnect()
1.0.0b4
Breaking change: `getDirectorBearerToken()` in `account.py` returns token time valid in seconds, instead of a `datetime.datetime` object representing the token expiry time. Conversion to a datetime is left as a task for the library user.