Remove now-unused node_modules directory

We switched to system-wide node module more than a month ago.
Remove more unused dirs: studenti ssl

We have been using /var/lib/rivoluz for more than a month now.
html/private.tpl.html: be more clear

Explain to students that the version saved after the deadline is
the only one that matters.

Previous versions may be saved for testing, therefore, they may see
that the saved post does not reflect the latest version, before the
post-publication deadline has expired.
processing += run.sh: script to run stuff in processing

Basically, the script helps because it sets the environment
variables that tell node.js where extra modules (installed with
npm) are.
rivoluz: we now change dir in run.sh
Merge remote-tracking branch 'highgarden/master'