* Several tests were marked as FIXME and should have been fixed with
the boto3 move.
* Improved tags output. Add purge_tags option (default: no)
* Allow description and tags update
* Return launch_permissions
* Allow empty launch permissions for image creation
* Empty launch permissions should work the same way for image
creation as no launch permissions
* Cope with ephemeral devices in AMI block device mapping
* Ephemeral devices can appear in AMI block devices, and this information should be returned
* Fix notation for creating sets from comprehensions