rbac validate_request fails at random
rbac validate_request fails at random

Description: roles were none because HTTP_X_ROLES
were missing in the request. None object when iterated,
causes this trace. If roles are not present, such
requests are rejected. But, why are roles not present?
So, this is a partial fix.

Change-Id: I4d9dd1bfc319f5cce73a5195b9435de74d70497d
Partial-Bug: #1716311

nischalsheth/contrail-controller,eonpatapon/contrail-controller,eonpatapon/contrail-controller,rombie/contrail-controller,eonpatapon/contrail-controller,nischalsheth/contrail-controller,nischalsheth/contrail-controller,nischalsheth/contrail-controller,eonpatapon/contrail-controller,rombie/contrail-controller,nischalsheth/contrail-controller,nischalsheth/contrail-controller,eonpatapon/contrail-controller,rombie/contrail-controller,rombie/contrail-controller,rombie/contrail-controller,eonpatapon/contrail-controller,rombie/contrail-controller,rombie/contrail-controller,nischalsheth/contrail-controller,nischalsheth/contrail-controller,eonpatapon/contrail-controller