devstack: enable odl-neutron-logger by default
devstack: enable odl-neutron-logger by default

When odl-neutron-logger is available (from Boron),
enable odl-neutron-logger by default for debugging.

Change-Id: Iccbec823925195fcab520cc010660a68796da20e

openstack/networking-odl,openstack/networking-odl,openstack/networking-odl