Expand Designate RBAC testing - zone transfer acc

This patch adds RBAC testing for allowed and disallowed credentials.
This is one of a series of patches adding testing. This patch covers the
zone transfer accept API.

This patch also updates the list_transfer_accept service client to
return results consistent with the other "list" service clients.

Change-Id: I0a6145e8b348fdbe68dd5518dc7b6720fbaae8db
2 files changed