Created a login.html template for the LoginForm class.
It extends from base.html and adds the login functionality. Extending from the base template ensures a consistent layout across all pages.
form.hidden_tag() template arg gets replaced with a hidden field which implements CSRF prevention that was enabled in config.py.
The openid field has a width of 80 chars.
As we don't have a submit button defined in the form class, we define it here as a regular field.