Cache volume and clean cache button for Admin->Sharelatex

Created by: dtu-compute

02323 and 02402's enotes takes hours to compile on a fresh cache.

In get-pdf this happens for all courses

e="/tmp/$course"
unzip $z -d $e
cd $e

get-pdf should then -V /enote/cache:/cache and each course can then do

mkdir -p /cache/$course
rm -rf cache
ln -s /cache/$course cache

The Admin-Sharelatex->"Clear cache" button would then rm -rf /enote/cache/$course.