Switch settings to use "the one true way" approach

The advantage of this approach is that the production and dev configurations are
in version control, so there's less opportunity for surprises.

As advocated by Jacob Kaplan-Moss (OSCON 2011) and Two Scoops of Django book.

Document the new deployment approach

Also mentioned linkchecker.

Remove documentation reference to unused `djangopw` module

Code appears to have been removed some time back.