[py3] ensure AjaxController return bytes
publish() must return bytes, when the @ajaxfunc decorated method return None, this raised:
TypeError: You cannot set Response.body to a text object (use Response.text)
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