[js] simplify cw.log implementation
There's no need to rebuild and array and join its content, just
call console.log with ``arguments``.
The only trick is that console.log must be called on a console instance.
usr/lib/PY_VERSION/*-packages/cubicweb/web
usr/lib/PY_VERSION/*-packages/cubicweb/wsgi
usr/share/cubicweb/cubes/shared/data
usr/share/cubicweb/cubes/shared/wdoc