Some functions into student model for checks that will be added to studentscontroller and squash some bugs.
Most of the StudentsController CSV upload bugs still exist (duplicate entries if CSV uploaded multiple times - will be squashed in near future - thank you for your patience)y
Merge branch 'devel' of github.com:Meta-arviointi/meta-arviointi into devel
Navigation v1 ready, NOTICE: moved index() from courses to students
small css tweaking
Merge branch 'devel', navi changes