Added ability to refer to self and to other SG Helpers

Minor orchestration added to allow a rule to be converged again at a
later state.
Core now supports named resources and resource 2nd stage convegence

Resources can now refer to each other by the heet base name preceeded
with an '@' character. As well, resources have a way to register a
converge_depedency() method that will run at program exit and can be
used to try to reconverge certain attributes that could not be converged
the first time around for some reason.