Fix error in .gitlab-ci.yaml that would cause builds on master not to be deployed in testing environment

Replace some occurences of and_then() by map() as suggest by clippy lint clippy::bind-instead-of-map

This reverts commit 60faa7ed.

Make sessions last 12 hours instead of 1.5, ignore 'permanent_login' as cookies are browsersession-based anyways

Ask users on OAuth login to fill in their user data (especially grade). Fixes #96. Also some formatting

Template jwinf: Set viewport-width on contest page as well to make it not stand outh that much on mobile devices

Admin page: Contest export: Add index.html to export directory to protect exports from being exposed on misconfigured webservers