Configure an authorized user for the QPID broker

If QPID_USERNAME is set, add the user to the QPID broker's
authentication database.  Use the value of QPID_PASSWORD as the
password for the user, prompting for a password if QPID_PASSWORD is
not set.  This requires that all clients provide this username and
password when connecting to the QPID broker, or the connection will be
rejected.

If QPID_USERNAME is not set (the default), disable QPID broker
authentication. This allows any client to connect to the QPID broker
without needing authentication.

Change-Id: Ibd79873379740930ce5f598018c1ca1fffda7c31
Closes-Bug: 1272399
Merge "Configure an authorized user for the QPID broker"