Adding a SERVICE_HOST as a default for BAGPIPE_BGP_PEER
Adding a SERVICE_HOST as a default for BAGPIPE_BGP_PEER

This allows not to specify a peer on all-in-one or multinode
devstack deployments, with the fake-rr on the SERVICE_HOST.

stackforge/networking-bagpipe-l2,openstack/networking-bagpipe,openstack/networking-bagpipe-l2,stackforge/networking-bagpipe-l2,openstack/networking-bagpipe-l2,openstack/networking-bagpipe