Generate an IPv6 address when PUBLIC_BRIDGE does not have one

Closes-Bug: #1400823
Change-Id: Ic79fd003aea2af7b258397ec2cdfd70c8568743c
Take an optional rabbit user name as input

Newer versions of rabbitmq (3.3 and later) do not allow the 'guest'
user to access on non-local interfaces.

- Added a new config RABBIT_USERID which defaults to stackrabbit
- Invoked config scripts using that variable

Adopted from:
https://review.openstack.org/#/c/107779/

Change-Id: I43a231c9611b4cc2e390b603aa3bfb49c915bdc5
Closes-Bug: #1343354
Co-Authored-By: Scott Moser <smoser@ubuntu.com>
XenAPI: Simplify installed packages

Remove duplicate packages.
pip is handled by devstack, so don't try and install it here.

Change-Id: I6f22e0f86ae071d30bf69de9ed5dec6b28ebc92b
Merge "Take an optional rabbit user name as input"
Merge "Generate an IPv6 address when PUBLIC_BRIDGE does not have one"
Merge "XenAPI: Simplify installed packages"