Access checking based on role

Adopting the usual permission checking mechanisms based on role to access different areas/views of the website.

app/utils/decorators.py

@@ -22,6 +22,6 @@ def students_only(func):
     def inner(*args, **kwargs):
         if current_user.role == STUDENT:
             return func(*args, **kwargs)
-        return redirect(url_for(current_user.role + ".projects"))
+        return redirect(url_for(f"{current_user.role}.projects"))
 
     return inner