Updated Chapter 2: Admonition 'Django and Python 3.0'

Cheers.  Hope this passes muster.
My first time trying to contribute.

Updated a couple of points in the 'Django and Python 3.0' admonition
section:
1. Made it clear that the compatibility issues exist for the 3.x
series, not just 3.0.

2. Made it clear that Django as of version 1.4 doesn't support Python
3.x

3. Changed the verb tense in a couple of places to made it fit the
context more appropriately.