#341 removed additional promote demote stuff
removed deleted branch from travis.yml
migrations for new models
removed devise and implented usual login procedure
staff and student scopes and controllers
student registration and login
foreign keys to students
students show page for new student model
Abilities for new user models + new test login helper
firing for students (not users)
Login helper for controllers
no staff updating anymore -> update user
student creation abilities
create job_offers as admin
moved frequency from user to student
applications for users
new user and student unit tests
basic staff creation
updated ability
basis student editing