Adding octavia required roles

Adding following role which is reuqired by octavia services

- load-balancer_observer
- load-balancer_global_observer
- load-balancer_member
- load-balancer_admin
- load-balancer_quota_admin

Change-Id: I6f351c96915b09cb9a6ef716515b45785d62cb90
Closes-Bug: #1745915