Refactor common code from UsecasesEventManager

Refactor common code from UsecasesEventManager

Created ClEventManagerWithSteps, as a subclass of
ControlLoopEventManager.  It contains the "Steps" to be performed and
also deals with outcomes.
Created ClEventManagerWithEvent, as a subclass of that.  It contains a
VirtualControlLoopEvent object, and uses that to populate data used by
the superclass.
Updates per review comments:
- made loadPolicy() protected
- refactored another level to manage operation outcomes

Issue-ID: POLICY-3262
Change-Id: Ibf5dd114746ae26e04fe37d562273fc81dd8cfbe
Signed-off-by: Jim Hahn <jrh3@att.com>