Updated neutron.conf to reflect new RPC options

After oslo.messaging port, some option became unavailable to set, some
of them changed description or default values. Make sure we don't leave
anything related to old RPC layer there.

New entries are generated by calling the following from inside
oslo-incubator:

$ python openstack/common/config/generator.py -l oslo.messaging

blueprint oslo-messaging

Change-Id: I1523309cf0cd92a5d5f0b265f49979b3e47c2afa
Pass newly created router to _update_router_gw_info

pass it to _update_router_gw_info as last parameter to save
retrieving it again from the session.

Change-Id: I7fbbd675839c2874578c62dfed390d86e3b4801a
Add sanity check for nova notification support

Since nova notification support adds a runtime dependency on
novaclient, add an external sanity check testing the system's
ability to import neutron.notifiers.nova

Change-Id: I8a72c8763bb69a01178fc4ec91071a64a4648aab
Closes-bug: #1334412
Merge "Pass newly created router to _update_router_gw_info"
Merge "Add sanity check for nova notification support"
Merge "Updated neutron.conf to reflect new RPC options"