[cleanup] Fix some flake8 errors and drop upper bound of copyright along the way. autoform module is not added to flake8-ok-files since there are some remaining errors to be handled, but that's still a start.

missing-dep-for-interpreter make => make | build-essential | dpkg-dev (usr/*/cubicweb/skeleton/debian/rules)
embedded-javascript-library usr/share/cubicweb/cubes/shared/data/jquery.js