L2GW: make use of neutron_lib constants

Commit 87a79256c494c36f2d9597313f430b24c0110161 added neutron_lib
for shared constants. This patch moves us to make use of the
aforementioned library.

Change-Id: I9f8c04d710bff2323d8259634097ea1738c50cdf

networking_l2gw/services/l2gateway/ovsdb/data.py

@@ -13,7 +13,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from neutron.common import constants
 from neutron import manager
 from neutron.plugins.ml2.drivers.l2pop import rpc as l2pop_rpc
 
@@ -26,6 +25,7 @@ from networking_l2gw.services.l2gateway.common import topics
 from networking_l2gw.services.l2gateway import exceptions as l2gw_exc
 from networking_l2gw.services.l2gateway.service_drivers import agent_api
 
+from neutron_lib import constants
 from oslo_config import cfg
 from oslo_log import log as logging
 import oslo_messaging as messaging

networking_l2gw/services/l2gateway/service_drivers/rpc_l2gw.py

@@ -14,7 +14,6 @@
 #    under the License.
 
 import abc
-from neutron.common import constants as n_const
 from neutron.common import exceptions
 from neutron.common import rpc as n_rpc
 from neutron.db import agents_db
@@ -31,6 +30,7 @@ from networking_l2gw.services.l2gateway import exceptions as l2gw_exc
 from networking_l2gw.services.l2gateway import service_drivers
 from networking_l2gw.services.l2gateway.service_drivers import agent_api
 
+from neutron_lib import constants as n_const
 from oslo_config import cfg
 from oslo_log import log as logging
 import oslo_messaging as messaging

requirements.txt

@@ -4,4 +4,5 @@
 
 pbr>=1.6 # Apache-2.0
 Babel>=1.3 # BSD
+neutron-lib>=0.0.1  # Apache-2.0
 python-neutronclient>=2.6.0 # Apache-2.0