Medium: PE: Master internal ordering enhancements. Added stopped->start, stopped->promote.
These can be required when some instances are stopping and being promoted
but none are being started.
The normal sequence would be demote->stop->start->promote but this broke down
when a step was missed and these explicit ordering constraints we not present.

Mercurial revision: caed3c043a1dd4f6e926732a700eafd0f269712d