Description of problem:
Whene supplying broker address as IPv6 literal (ex. [IPv6]) the qpid-cluster
fails to connect. It's probably tries to resolve literal as domain name.

Version-Release number of selected component (if applicable):
qpid-tools-0.12-2.el6.noarch
python-qpid-0.14-1.el6.noarch
python-qpid-qmf-0.14-3.el6.x86_64

How reproducible:
100%

Steps to Reproduce:
1. start up cluster with --cluster-url with IPv6 able broker (ex.
amqp:tcp:[IPv6])
2. run qpid-cluster -C 127.0.0.1
3. observe that qpid-cluster fails


Actual results:
Traceback (most recent call last):
  File "/usr/bin/qpid-cluster", line 311, in <module>
    sys.exit(main())
  File "/usr/bin/qpid-cluster", line 302, in main
    raise Exception("Failed: %s - %s" % (e.__class__.__name__, e))
Exception: Failed: Exception - Invalid URL 2

Expected results:
qpid-cluster lists active connections

Additional info: