django: Change DB query so that it orders posts by timestamp
django: Specify the ordering in the model

If we set our preferred ordering in the model, any other Django-based app
or project that accesses our data will use that ordering.
django: Add a simple form to add blog posts
django: Add CSRF token to the HTMl form

Django comes with a data-preserving feature that disallows POSTs which are
not secure against cross-site request forgery (CSRF) attacks.


References:
http://docs.djangoproject.com/en/dev/intro/tutorial04/#write-a-simple-form
http://docs.djangoproject.com/en/dev/ref/contrib/csrf/
django: Use django's Forms to generate our HTML

This way, we avoid duplication because we were specifying the fields in
both the HTML and the Python codes.

We still have duplication, but at least now it's only on one of the two
sides.
django: Use ModelForm instead of Form to avoid code duplication

Note that we need to:
1) Exclude the timestamp from the form
2) Set the timestamp in the view `create_blogpost`