Url and Page classes used to encapsulate the "site map" information (URL
regular expressions, Django views, menu item names, etc.) and the relation
between pages in the site map.
There are still lots of TODOs in this first pass.
Patch by: Todd Larsen
Review by: to-be-reviewed
This is an optional add-on app, flatpages.
For full documentation, see either of these:
* The file docs/flatpages.txt in the Django distribution
* http://www.djangoproject.com/documentation/flatpages/ on the Web
Both have identical content.