This commit renames flavor_ref to flavor_id and adds the flavor_name
parameter. Users can now specify either a flavor ID or name when launching
instances.
This commit renames image_ref to image_id and adds the image_name
parameter. Users can now specify either an image UUID or image name
when launching instances.
image_name is preferrable as deployers/sysadmins generally regularly
deprecate/remove outdated and insecure images. Using a consistent
naming scheme allows end-users to always retrieve a working image.