Fix for Broken HipChatAdapter.Reply method

Honestly not sure how or even IF this worked before, but I've fixed it.
Apparently you need the fully qualified user@host to be passed into the
Jid constructor.

Since that's only available via the _roster dictionary which is keyed on the numeric ID, I have to do a list scan by user name to get the hipchat numericID.  Definitely open to a better way of doing this if anyone sees it.