Modifying workflow api data model to be WSME complaint

WSME 0.8.0 adds strict attribute checking. Currently
we are passing base_url as part of the data that is
sent from REST requests from python-solumclient.
So adding base_url to the workflow data model.

Closes-Bug: #1491504

Change-Id: I14edb2ef9945d75e4cd9ff54c0a4354e2875a57b

solum/api/controllers/v1/datamodel/workflow.py

@@ -26,6 +26,14 @@ class Workflow(wtypes.Base):
 
     A workflow maintains a living creation and deployment of an App.
     """
+
+    # (devkulkarni) Added base_url to get around strict validation
+    # checking of WSME 0.8.0
+    # https://bugs.launchpad.net/solum/+bug/1491504
+    # https://bugs.launchpad.net/solum/+bug/1491499
+    base_url = common_types.Uri
+    "URI of the base resource."
+
     uri = common_types.Uri
     "URI to the resource."
 
@@ -92,4 +100,4 @@ class Workflow(wtypes.Base):
             if getattr(self, a) is None:
                 continue
             base[a] = getattr(self, a)
-        return base
+        return base