Replace examples using the outdated Django-1.4.2 with the latest version, Django-1.5.1.

[jamesbrewerdev]

Django-1.5.1 is the latest version, so it makes sense that the examples for how to install Django should use 1.5.1 instead of the outdated 1.4.2. Also, Django no longer supports Python 2.5, so I've updated the book to noted support for 2.6.5-2.7.

[MortalCatalyst]

Should we be including the more common methods of using pip easy_install and vitrualenv ?

[jamesbrewerdev]

I think that's a good idea. I suppose when the book was originally written there was no easy_install or pip install for Django and that's why the book doesn't mention it.