remove dns override

The dns settings can be overridden in the openstack
tenant subnetwork settings

Change-Id: I36e3d012e5b28fa953599c0c0828bda40a67053d
add wait_for_boot variable

Change-Id: Iac4b68a50b6cab4cb149833077f52a5af4c76b70
Add support for a separate tempest node

Icehouse-3 has dropped all support for tempest on py2.6/nose.
This allows for a separate tempest node, with a separate image id,
flavor, and user.

Change-Id: I9b3718d692eddaad8558bd16ff5832f4dccd7d93