hipchat: 'chat add hipchat "channel name"' now tries to guess the JID
It's basically prepending the organization id, appending the default MUC
host from the success packet, and generating a slug based on the name
for the middle part, which is replacing a few characters with
underscores and doing a unicode aware lowercasing.
Includes tests, which are useless other than validating the initial
implementation with the test vectors that i already tested manually.
Guaranteed to detect zero breakages in the future. Good test code.
