CORD-1951 fix and cleanup vEG synchronizer

Change-Id: I938edf40da13192614fa16ecf350bd18bea84f8d
(cherry picked from commit 8e56c00757e05a18e059772a5524c982d49781f9)
diff --git a/xos/synchronizer/wrappers/veeserviceinstance.py b/xos/synchronizer/wrappers/veeserviceinstance.py
new file mode 100644
index 0000000..c82a0c8
--- /dev/null
+++ b/xos/synchronizer/wrappers/veeserviceinstance.py
@@ -0,0 +1,49 @@
+
+# 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.
+
+
+from xosapi.orm import ORMWrapper, register_convenience_wrapper
+
+class ORMWrapperVEEServiceInstance(ORMWrapper):
+    @property
+    def veg(self):
+        links = self.stub.ServiceInstanceLink.objects.filter(subscriber_service_instance_id = self.id)
+        for link in links:
+            # cast from ServiceInstance to VSGTenant
+            vegs = self.stub.VEGTenant.objects.filter(id = link.provider_service_instance.id)
+            if vegs:
+                return vegs[0]
+        return None
+
+    # DEPRECATED
+    @property
+    def vcpe(self):
+        return self.veg
+
+    # DEPRECATED
+    @property
+    def vsg(Self):
+        return self.veg
+
+    @property
+    def subscriber(self):
+        links = self.stub.ServiceInstanceLink.objects.filter(provider_service_instance_id = self.id)
+        for link in links:
+            # assume the only thing that links to a VEE must be a subscriber
+            if link.subscriber_service_instance:
+                return link.subscriber_service_instance.leaf_model
+        return None
+
+register_convenience_wrapper("VEEServiceInstance", ORMWrapperVEEServiceInstance)