Move three more manpages from systemd to libsystemd-*-dev as appropriate.

These are actually links to manpages already moved to libsystemd-*-dev,
so currently man throws an error if you try to view them without the
appropriate -dev package.
Remove pre-generated rules and unit files in debian/rules clean target.

These are generated with rootprefix=/usr and so has the wrong paths for Debian.
Merge branch 'experimental' into bartholomea