Description of problem:

Various people have complained that from a usability (versus engineering)
standpoint, "resourcegroup" is inappropriate to describe what in fact rgmanager
handles.  Thus, "resourcegroup" needs to be renamed back to the traditional
"service" nomenclature to reflect what existing users of clumanager have come to
expect.

The unit of failover is the service - which is the same thing as a resource group.

system-config-cluster already reflects this change.

This underlines a small problem in rgmanager: rgmanager should use the "root"
special attribute tag to find root resources, not assume a static string as it
has been.  This is a small change.