Make garbd init script LSB compliant.
The init file must be LSB compliant. For details see https://wiki.debian.org/LSBInitScripts
This includes that exit code must by default be 0. Non-zero exit values should be emitted
strictly only when the script fails. If not so, then for example installing and directy after
that removing the package would fail as the package manager things a non-zero exit code
from 'service stop' means it failed to stop.