quiz/website: remove git and github

Created by: dtu-compute

Depends on #85.

Quiz and website have all their files in

vol/xxxxx/{pages,quizzes,uploads,sharelatex-{private,public,backups}}

sharelatex-private  : enotes are built here
sharelatex-public   : enotes are moved to here to appear in the menu
sharelatex-backups  : nightly dumps made by your backup script