strays/missing on sr3 status during start or stop

[petersilva]

there is a window of time while "stop" and "start" operations are in progress, where the status will be marked as missing because either instance processes have been killed but the pid files not removed (stopping) or the instance processes have been launched, but not yet written their pid files so they can be claimed.

so sr3 sanity if runing while a flow is being stopped, will restart it, rather than allowing the stop to complete. When in start up, sr3 sanity can kill some instance processes that are marked stray because they have not fully initialized yet, and then restart those instances.

sub-optimal.

[petersilva]

left-over from #1067