CORD-1849 Split XOS code out of OLT and VTN repos

Change-Id: I307b2a9a54fdcdab14e6bf96d9a9b060ff421a77
diff --git a/xos/header.py b/xos/header.py
new file mode 100644
index 0000000..0bb8be2
--- /dev/null
+++ b/xos/header.py
@@ -0,0 +1,39 @@
+
+# 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 django.db import models
+from django.db.models import *
+from core.models import Service, XOSBase, Slice, Instance, ServiceInstance, ServiceInstanceLink, Node, Image, User, Flavor, NetworkParameter, NetworkParameterType, Port, AddressPool, User
+from core.models.xosbase import StrippedCharField
+import os
+from django.db import models, transaction
+from django.forms.models import model_to_dict
+from django.db.models import Q
+from operator import itemgetter, attrgetter, methodcaller
+from core.models import Tag
+from core.models.service import LeastLoadedNodeScheduler
+from services.vrouter.models import VRouterService, VRouterTenant
+from services.rcord.models import CordSubscriberRoot
+import traceback
+from xos.exceptions import *
+from xosconfig import Config
+
+class ConfigurationError(Exception):
+    pass
+
+VOLT_KIND = "vOLT"
+
+CORD_USE_VTN = getattr(Config(), "networking_use_vtn", False)