Abstract: Improved email function, several bug fixings, preparations for new things to come

– Until now we had two different ways of sending email. This has now been merged to one system. SMTP configuration now only takes place in camai/passwords.py. The SMTP configuration in the DB table tools_settings is now obsolete.

– We fixed a couple of minor bugs. Everyone who saw strange things with 1.4.0 should try again with this version.

– Under the hood we implemented the infrastructure for a quota system. This will help the Raspi user to prevent their system from running full and get stuck.