Allow cluster search to be more flexible. Defaults to existing role search, but allows for search via recipes/roles within a nodes run_list.

[pdunnavant]

In cases where roles are not used, this allows a wrapper cookbook to set node[:aem][:author][:cluster_role], node[:aem][:publish][:cluster_role], and/or node[:aem][:dispatcher][:cluster_role] to recipe[wrapper-author], recipe[wrapper-publish], recipe[wrapper-dispatcher].

This defaults to the role search that existed before, so this won't break any existing functionality.