Apply the same pattern to the other virtual class rooms and make the
time out configurable

Add quota of concurrent meetings per template, add informations while
selecting a template, check server availability, show the template of
the meeting in admin./edit table, permanent meeting can be disabled,
dates of non-permanent meeting are strictly observed and mandatory,
duration of meeting is exact (+ 1 minute)...

Use an opt-out flow for comments in video, springify notifications and
notifications handlers