move ssh key setup to its own recipe

I wanted the ssh key setup stuff in my wrapper cookbook, but I didn't want the machine setup from the cluster-provision recipe.

I put it in a new recipe rather than combining it with the setup-provisioner.  Both are nice and clean this way.

Thoughts?  Better recipe name?

Tested successfully in my wrapper cookbook.
I wonder if we shouldn't just require this in say a library that will be evaled when loading the cookbook such as in the helpers?