xenapi - quantum: L2 agents for dom0 and domU

This patch makes it easier to support the all-in-one installation of
XenServer with Quantum:
- separate agents for domU and dom0 openvswitches. The domU agent's name
  is "q-domua", and the dom0 agent is called "q-agt"
- create a physnet1 physical network to connect those openvswitches

Note: This patch depends on the quantum patch:

    https://review.openstack.org/15022

For a diagram, see:
    http://goo.gl/BuAdg

Change-Id: Iff851438553528b9051edd380ecbb2c0415cbf78
Functions are required to parse localrc

This is essentially a revert of
73695d0ea490c4c7a1158957dd5a85586cfa0933. Since stackrc is
responsible for sourcing localrc, the required functions
are necessary (like for enable_service).

fixes bug 1186488

Change-Id: Iad90f802e77b94416821008c294c1a2ede8a4729
Merge "xenapi - quantum: L2 agents for dom0 and domU"