Users can see the superuser account but cannot add them as tutors

[Nppatel97]

When a user tries to add a superuser as a tutor, it displays ERROR 400 "This page isn't working".

[AhmedNSidd]

More info: The reason why this is happening is because shreyas's account is a superuser account of schedulearn, so he can't be added as a tutor. The solution is two-fold: Edit the search view so it doesn't search a superuser's account. The next solution is to edit the add_tutor and add_student views to check if the user is a superuser account, if it is, then return an error/prevent that addition.