Add configuration option `networks`, a list of network UUIDs, to attach to the
source instance.
In some openstack installs, no default network will be attached or the network
with the ability to attach a public floating IP will need to be specified.
Many cloud providers have a minimum charge of 1 hour, and if there are DNS problems we can hit the 1 minute timeout easily.
Waiting five minutes gives more of a margin of error.
This change adds base support for an openstack builder.
Thank you to Rackspace for providing cloud assets to complete this work
and @sam-falvo for working with us on the perigee/gophercloud changes.