Medium: raft: delay revoke if there's another operation in progress

In case a heartbeat was just sent out and the user wants to
revoke the ticket, better wait a bit until we get all the acks.
Medium: raft: invalidate ticket if the leader wants to step down
Low: service-runnable: remove crm_simulate's tmp shadow (bnc#879934)
Low: test: add test for external program failure
Medium: raft: on server step down reset the ticket state too

And write the ticket to the CIB. We don't have the ticket
anymore.
Low: test: add test applicability test
Low: doc: move the user/group parameters to a better place
Low: test: add simultaneous start test
Dev: add some debugging
Medium: raft: don't reset acks prematurely (bnc#881508)
Dev: test: update/cleanup