This change causes neutron-dynamic-routing to stop consuming Ryu
in favor of os-ken. os-ken becomes the reference implementation
for BGP services and neutron-dynamic-routing no longer has a
dependency on Ryu.
Partially-Implements: blueprint ryu-framework-maintenace-transition
Change-Id: I4a68440809cad5de2d6d191f7211d68b542672e5