Ensure datetimes can be properly serialized.

The nova-network manager was returning db models from methods invoked
via rpc.call(). These db models include non-primitive types that can
not be properly serialized (namely datetime objects). Use
to_primitive() to ensure that the data gets serialized properly.

Fix bug: #1089430

Change-Id: I0519e88444b8fcc3af5e43170ea07dd966ccef05
Signed-off-by: zhiyanliu <lzy.dev@gmail.com>

nova/network/manager.py

@@ -1912,7 +1912,7 @@ def get_instance_id_by_floating_address(self, context, address):
     @wrap_check_policy
     def get_network(self, context, network_uuid):
         network = self.db.network_get_by_uuid(context.elevated(), network_uuid)
-        return dict(network.iteritems())
+        return jsonutils.to_primitive(network)
 
     @wrap_check_policy
     def get_all_networks(self, context):