Modified Student.distributions_todo

- Created 3 separate requirement categories (language, qrbasic,
distribution) to fit student needs (i.e some students tested out of
language, qrbasic, etc)
- Modified DIST_REQ to represent all 3 distribution areas
- Added fields qrb_passed and foreign_lang_passed to Student
- Created new distributions_todo method
Merge branch 'master' of https://github.com/lilsplat/bowser
Merge branch 'master' of https://github.com/lilsplat/bowser