Glance configuration changes

This change does the following:

- moves to static templates for glance configs
- updates glance-api.conf to conditionally write configuration blocks based on options (see swift_store_* and rabbit_*)
- makes notification_driver configurable and sets a default for notification_driver (noop)
- sets a default for swift_store_endpoint_type (internalURL)

See individual commits for more info.

Closes https://github.com/rcbops/ansible-lxc-rpc/issues/29 and https://github.com/rcbops/ansible-lxc-rpc/issues/90