Changes to glance configuration options in Juno

[ionosphere80]

On 10.0.0rc1, attempting to create an image using the default 'file' datastore returns the following error:

410 Gone
Error in store configuration. Adding images to store is disabled.

Further investigation reveals this bug regarding the [glance_store] section in the configuration files:

https://bugs.launchpad.net/glance/+bug/1380689

See also:

http://docs.openstack.org/trunk/config-reference/content/glance-conf-changes-master.html

[ionosphere80]

Further investigation led to issue #364. Glance still works after restoring the deprecated options, but we should probably fix them anyway.