handle impending oslo.messaging deprecation

When running trove, I see this deprecation message.

/usr/local/lib/python2.7/dist-packages/oslo_messaging/rpc/server.py:200:
FutureWarning: The access_policy argument is changing its default
value to <class
'oslo_messaging.rpc.dispatcher.DefaultRPCAccessPolicy'> in version
'?', please update the code to explicitly set None as the value:
access_policy defaults to LegacyRPCAccessPolicy which exposes private
methods. Explicitly set access_policy to DefaultRPCAccessPolicy or
ExplicitRPCAccessPolicy.access_policy)

For now, I'm setting this to LegacyRPCAccessPolicy, will be making
other changes in this area before long and will make our own access
policy anyway.

Change-Id: Ib0dc68620bbd6105349c10976695c502f6d76c13
Depends-On: Id5be526a0418db5d00cbf5cbceb4993274989e72

trove/rpc.py

@@ -31,6 +31,7 @@ __all__ = [
 
 from oslo_config import cfg
 import oslo_messaging as messaging
+from oslo_messaging.rpc import dispatcher
 
 import trove.common.exception
 from trove.common.rpc import secure_serializer as ssz
@@ -118,11 +119,13 @@ def get_server(target, endpoints, key, serializer=None,
     serializer = secure_serializer(
         sz.TroveRequestContextSerializer(serializer), key)
 
-    return messaging.get_rpc_server(TRANSPORT,
-                                    target,
-                                    endpoints,
-                                    executor=executor,
-                                    serializer=serializer)
+    return messaging.get_rpc_server(
+        TRANSPORT,
+        target,
+        endpoints,
+        executor=executor,
+        serializer=serializer,
+        access_policy=dispatcher.LegacyRPCAccessPolicy)
 
 
 def get_notifier(service=None, host=None, publisher_id=None):