Added checks for proper handling of systemd unit files

This checks for proper handling of systemd unit files. For every .socket/.service file that is copied to /usr/lib/systemd/system it is checked that
- %pre contains %service_add_pre 
- %post contains %service_add_post
- %preun contains %service_del_preun
- %postun contains %service_del_postun
for this file