add html template for 403 and update settings with TEMPLATE_DIR
implement register student form and view
update school views

add add category/lesson in views
add according modelforms in forms
make category name unique
update urls accordingly
add files

migration file for unique category name
html template files for lesson and category
add/update html templates

put template of auth inside app folder
change auth views accordingly
make teacher nav html template
include teacher nav in other teacher templates
add question/lesson forms

update views and urls
add logout link in teacher nav template html
swap decorators position in school views

first require login then check if teacher and raise