BZ #1045137 - Ensure physcial ports added to ovs bridge on networker.

https://bugzilla.redhat.com/show_bug.cgi?id=1045137

Move configuration of bridge and ports to the bridge_uplinks parameter
of ::neutron::agents::ovs

Example value for the ovs_bride_uplinks parameter in networker.pp:
["br-em2:em2","br-p3p1:p3p1"]