kubecfg doesn't allow updates because of path checks

Check for 1 path segment on create/list, 2 on update/delete, and
allow any number of path segments on get (for now).

Also pretty prints the list of actual types that are supported for
create/update, which today corresponds to the list of types that
are supported period.
Merge pull request #570 from smarterclayton/kubecfg_cant_update

kubecfg doesn't allow updates because of path checks