[CORD-2938] Moving convenience methods in the synchronizer containers

Change-Id: Idd8505d664396e9b218ba05e7613e86733b48fc7
diff --git a/xos/synchronizer/models/convenience/addressmanagerservice.py b/xos/synchronizer/models/convenience/addressmanagerservice.py
new file mode 100644
index 0000000..6c59bec
--- /dev/null
+++ b/xos/synchronizer/models/convenience/addressmanagerservice.py
@@ -0,0 +1,31 @@
+
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+import json
+from xosapi.orm import ORMWrapper, register_convenience_wrapper
+from xosapi.convenience.service import ORMWrapperService
+
+class ORMWrapperAddressManagerService(ORMWrapperService):
+    def get_gateways(self):
+        gateways = []
+
+        aps = self.addresspools.all()
+        for ap in aps:
+            gateways.append({"gateway_ip": ap.gateway_ip, "gateway_mac": ap.gateway_mac})
+
+        return gateways
+
+register_convenience_wrapper("AddressManagerService", ORMWrapperAddressManagerService)