First step towards REST + Vue Student Page

Backend
- Added isStudent permission
- Added serializers apropriate for StudentPage
- Added api-endpoint urls
- Added views regarding StudentPage
- Migrated the Django Session Authentication to djangorestframework-jwt authentication

Frontend
- Migrated from vue-resource to axios because of better documentation & features
- Added Login Component
- Added First Part of StudentPage containing overview of exam and subissions

Closes #41
References #39