Remove invis-to-admin initial tenant.

We don't use it, it's for devstack demo purposes, which is
inappropriate for a production targeted deployment.

Change-Id: Iccd2c75661f5cbc9a4770ea93660126b2b1dfae7
Remove unneeded roles.

We only need the admin and member roles: the other ones were
illustrative from devstack, but not relevant to the current production
setup.

Change-Id: I32e601a3ecc97d6469043df824c8aae064c00d5e