Gate fix: Rename Member (legacy) to member role

Due to a recent change [0], Member role is no longer
being found, as it has been renamed to member. This is
causing all the member-based gates to fail. Because "Member"
is legacy [1], this patchset uses "member" instead of "Member"
during the devstack Patrole plugin for master. For n-1
and n-2 releases "Member" is still used.

This patchset also specifies which role was not found in
the system while trying to resolve roles CONF.identity.admin_role
and CONF.patrole.rbac_test_role in order to make debugging
easier.

[0] https://review.openstack.org/#/c/572243/
[1] http://git.openstack.org/cgit/openstack-dev/devstack/tree/lib/keystone#n355

Change-Id: I7b59bab164041b26ed8a1a798546e493f22f6edd
4 files changed