added empty submissions

README.rst

core/models.py

core/static/lib/css/codemirror.css

core/static/lib/css/custom.css

core/static/lib/css/dialog.css

core/templates/base.html

core/templates/core/feedback_card.html

core/templates/core/feedback_form.html

core/templates/core/student_startpage.html

core/views/submission.py

populatedb.py