This covers most of the features specified in:
http://specs.openstack.org/openstack/heat-specs/specs/juno/stack-breakpoint.html
The breakpoints are specified via hooks in the stack's environment.
The only thing missing from the blueprint is stepping through a stack.
Partial-Blueprint: stack-breakpoint
Change-Id: Iddc019464484af18ca6f21f11660649e30d63aca