* Removes restriction of have to have an IPv4 network to create and use an IPv6 network
* Modifies nova-manage network to require either an IPv4 or IPv6 network be passed
* Modifies nova-manage network to ignore FLAGS.use_ipv6 (what is passed on the command line is what you get)
* Modifies nova-manage network to list IPv4 and IPv6 on list, no longer lists IPv4 netmask as it is implied by the cidr for the network
* Modifies network/manage.py to allow for empty IPv4 assignments.
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