cinder volume service keeps retrying even code exception

Make sure that ProcessLauncher does not try to restart the failed
service. And make sure the ProcessLauncher exits, when the number
of the failed services equal the number of total services.

Fixes: bug 1167841
Change-Id: I818c754534c18a62d292e21f0c98086571fe0565
Merge "cinder volume service keeps retrying even code exception"