Remove unused imports
Print userfriendly message if not root

Closes: #751088
pkg_services: Check if a service is actually installed

So far we returned the full list from pkg_services. This is o.k.  for
many to one mappings like apache but not for one to many like openjdk.

To avoid to print out services that aren't installed check that
beforehand.
Remove unused imports
Fix informal message

Packages don't map shared objects
Move detect_distro to Distro