no need for an empty default recipe. People can read the documentation and figure out how to use it.

Change-Id: Iad77dfcbff7f5229cd7e7bad81186d00fd813f92
remove 'default[openstack-image][' and replace with 'openstack-image[' like the rest of the attributes

Change-Id: I48489ceb773c781596d090c7592fe5e3ab75f746
Merge "remove 'default[openstack-image][' and replace with 'openstack-image[' like the rest of the attributes"