Use upstream dashboard.html in our theme (old one from funmooc is keeped as reference)

Identified commits to backport from funmooc (task numbers do neot seems revelant):

git log --author="neurolit" -p lms/templates/dashboard.html
25f939c4bdf77cd9f222b9b01ecf8b589eba26fa

git log --author="antoviaque" -p lms/templates/dashboard.html
Fixes #14 - Dashboard: for future courses, number shouldn't be displayed
873bc87475624728efebaabab5299465bdac91be
ef74ce262bb194694a7a8f01cb708083de59307e
7e63ab46dbb8449467de227960825643cd0ea452
09fe0a62adf40ead6fb68926f6645190d5e567c2