[glance ] Create for all client and non-client lib xena branch

This creates the stable/xena branch for all client
and non-client libraries now that we are past the
lib freeze on September 02.

If a team wants to wait for a specific patch to make it to the library,
someone from the team can -1 the patch to have it held,or update that
patch with a different commit SHA.

Patches with no response will be merged by Friday, September 10.

Change-Id: I8ac7d6b26ae29bb4b2a799cb2936eef8cec3bf67

deliverables/xena/glance-store.yaml

@@ -15,3 +15,6 @@ releases:
     projects:
       - repo: openstack/glance_store
         hash: 6807722becf024ab44ce6ec23e0aca432b1da1c1
+branches:
+  - name: stable/xena
+    location: 2.7.0

deliverables/xena/python-glanceclient.yaml

@@ -15,3 +15,6 @@ releases:
     projects:
       - repo: openstack/python-glanceclient
         hash: 74a55bd2fc0bd5fcab75d6be197eff0882470da7
+branches:
+  - name: stable/xena
+    location: 3.5.0