[VVP] parameterizing devstack branch for install

- Also modifying default storage class override logic

Issue-ID: INT-1424
Signed-off-by: stark, steven <steven.stark@att.com>
Change-Id: If8981f3a59437e21617edb30a6bca06ee6fa36a2
diff --git a/deployment/aks/cloud.conf b/deployment/aks/cloud.conf
index 0865d7a..d37da0e 100644
--- a/deployment/aks/cloud.conf
+++ b/deployment/aks/cloud.conf
@@ -58,6 +58,7 @@
 DEVSTACK_VNET_NAME=
 DEVSTACK_SUBNET_NAME=
 DEVSTACK_DISK_SIZE=
+DEVSTACK_BRANCH=
 OPENSTACK_USER=
 OPENSTACK_PASS=
 OPENSTACK_TENANT=