Add API network support

Add API network support

- Create additional NIC on virtual deployment if API network is enabled.
- Include API network in clean
- Change keystone admin api network to admin network. This should have
  no effect when api network is disabled, as today's behavior is to
  fall back to admin network anyway. However, when api network is
  defined, we need to be able to reach overcloud from undercloud through
  keystone admin api network.

Change-Id: Ib0aea4a0daeed5878793530c10d8f8a1bbe5fd72
Signed-off-by: Feng Pan <fpan@redhat.com>