Take a swing at processes without screen

So close.   Soooooo close before.  The problems reduced to getting
the PID at the right place and setting the pgid properly.

This changes how _run_process() behaves and basically makes run_process()
unnecessary.  I didn't want to just dump it yet as it might be usefull in
general although DevStack doesn't use it anywhere else.  Grenade might
want it someday though...

I included the scripts I used to test this; tests/fake-service.sh and
tests/run-process.sh are quite rough around the edges and may bite.  They
should mature into productive members of the testing ecosystem someday.

Change-Id: I03322bf0208353ebd267811735c66f13a516637b
Merge branch 'reorder-stack.sh' into dt-test
Merge branch 'cinder-backend-netapp' into dt-test
Merge branch 'cinder-backend-solidfire' into dt-test
Merge branch 'kill-kill-kill' into dt-test
Merge branch 'erlang-b-gone' into dt-test
Merge branch 'conf-tempest' into dt-test
Merge branch 'test-service-functions' into dt-test
Merge branch 'exercise-refresh' into dt-test