Harden Django project configuration

Set session and CSRF cookies as secure for production.
Set HSTS header to let browser remember HTTPS for 1 year.

note_kfet/settings/base.py

@@ -24,6 +24,15 @@ ALLOWED_HOSTS = [
     os.getenv('NOTE_URL', 'localhost'),
 ]
 
+# Use secure cookies in production
+SESSION_COOKIE_SECURE = not DEBUG
+CSRF_COOKIE_SECURE = not DEBUG
+
+# Remember HTTPS for 1 year
+SECURE_HSTS_SECONDS = 31536000
+SECURE_HSTS_INCLUDE_SUBDOMAINS = True
+SECURE_HSTS_PRELOAD = True
+
 
 # Application definition