Update uninstaller to remove all services files

[new2f7]

Untested, please test. You can get rid of the commented code, uncomment them or just leave it as it is.

I came across this issue, because after --remove (I tried multiple init systems) the following files were still present:

/etc/init.d/osync-target-helper-srv
/etc/systemd/user/osync-target-helper-srv\@.service.user