Improve /app/restart_services.sh

[tcely]

• s6-rc-db has a useful list of bundles
• sc-rc list accepts bundles/services the same way
• s6-rc-db can expand multiple bundles
• s6-rc-db reports the type of a service
• Add is_a_longrun & only_longruns functions
• By default, restart all longrun services that are already up
• Do not try to restart essential services
• Remove find/grep work-arounds
• Remove the check for a bundle
• Remove the list of longruns and seevices

[meeb]

No comments from me, merge away when you're finished tweaking.