The change modifies the glance template tasks such that it's now
using the config_template action plugin. This change will make so that
config files can be dynamically updated, by a deployer, at run time,
without requiring the need to modify the in tree templates or defaults.
Partially implements: blueprint tunable-openstack-configuration
Change-Id: I13fc6f38679267a84104cae948517d185e9f4ece
1e46243fea