BZ #1122663 - Add Generic RHEL 7 and Ceph OSD node types

https://bugzilla.redhat.com/show_bug.cgi?id=1122663

This patch creates two new roles. A Generic RHEL 7 role and a Ceph OSD
node role. The Ceph OSD role does not have any additional configuration,
as the installation of Ceph will be handled externally.
Add notification of addl work when a ceph node is deployed

Ceph and Generic RHEL 7 nodes do nothing but have
quickstack::openstack_common applied. Give the user a notification when
a ceph node is deployed that additional steps are required.
Merge pull request #272 from bcrochet/bz/1122663

BZ #1122663 - Add Generic RHEL 7 and Ceph OSD node types