Added br-tun bridge installation code via InternalNetworkManager in cases when the Node is not ready for overlay.
In DevStack environement, the Controller node is also used as compute. But the OVS is not populated with the
appropriate internal networks (such as br-tun and the corresponding patch-ports).
Witht his commit, this condition is identified and appropriate installation is done on the br-tun and br-int.
Change-Id: I8f1f65da864bd8a016912b46dbed3ed9a926ef2e
Signed-off-by: Madhu Venugopal <mavenugo@gmail.com>