Update getpython3.com for Python 3.3, Blogofile 0.8.1, various edits

This pull request does three things:

1) renames base.mako to site.mako, making the site work with Blogofile 0.8.1.

2) updates the what-is-python3 section for Python 3.3.

3) makes various sentence edits, rearranges the section order to put 'Resources' sooner, fixes the github ribbon image, etc.

If you'd prefer to only accept some of these changes, please let me know and I can rearrange into multiple branches and pull requests.