Don't create Member role

Creating the "_member_" role and "Member" role creates confusion.
"_member_" has special significance to keystone, so we keep that.

Horizon is modified to use "_member_" as the default role in [1].
This change should be merged after that.

See also rhbz#984294 [2]

[1] https://review.openstack.org/#/c/60462/
[2] https://bugzilla.redhat.com/show_bug.cgi?id=984294

Change-Id: If4ed1c2c72ca67acad7b70651e68ff7ce68157dd
(cherry picked from commit 1dd4297243d6ce25115828d87302a72e9d3e1f72)
Merge "Don't create Member role" into stable/havana