Support configuration of domains via suboridnate charms that
implement the new 'keystone-domain-backend' relation type; these
charms will create domain specific configuration files in
/etc/keystone/domains, and will notify the keystone charm when
configuration is complete, and the domain is ready for creation
in the keystone database.
Subordinate charms can also request a restart of keystone by
setting or changing the value of the 'restart-nonce' key in the
relation.
Change-Id: Ia2b171e910d7f3a5e6e09ba5b18dddc0a734e57a
Partial-Bug: 1645803
27b84f5b13