Created Python section, added 3 programming books.

Added a Python section and added 3 free Python programming eBooks.

If for some reason the PDF links do not work for everyone then there is also the online chapter book versions here:

* [Making Games with Python & Pygame](http://inventwithpython.com/chapters/)
* [Invent Your Own Computer Games with Python, 2nd Edition](http://inventwithpython.com/pygame/chapters/)
* [Hacking Secret Ciphers with Python](http://inventwithpython.com/hacking/chapters/)