Fix lintian warning init.d-script-does-not-source-init-functions
Bump Standards-Version to 3.9.4 (no changes)
Bump debhelper compatibility to 9

Update versioned debhelper build-dependency accordingly
No more clean stamp files manually, done by dh_clean already
Use dh_auto_{build,install,clean}
Apply wrap-and-sort
Finally switch to a minimal dh7 style debian/rules file
Remove debian/README.source, no more need

… with source format "3.0 (quilt)"