Add group name and role selectors to pallet.clj
Fix providers task to use support-providers
Fix reporting on missing provider
Add service-properties and image-user to node-list
Implicitly set the default task transient service

The first transient service added with pallet.main/add-service will become the
default service.
Add a localhost compute service provider

The localhost provider enables localhost to masquerade as a node in any group.
Calling `run-nodes` on a localhost service will change the group name of the
localhost node.