get back message id

[knightq]

The send method does return only a boolean.
It should be more useful if it would give back a more complex object or an id to be able to send further messages related to the same context (see: https://www.hipchat.com/docs/apiv2/method/send_room_notification)

[rberrelleza]

It would be useful. The challenge is how to do it in without breaking backwards compatibility. PRs appreciated :)