Complete migration from Google Code

[techtonik]

• place a redirect from https://code.google.com/p/pydotorg/ to GitHub
• change license to CC0
  • add rationale that crediting is important and licensing is not
  • add rationale that code must be max reused
  • ask for no patents and non-own code in guidelines
• move wiki to README.md
  • cut the text
  • be inclusive (issue Improve pydotorg onboarding #1)
  • explain relationship to python.org
• process https://github.com/pydotorg/backlog/blob/master/Wiki.md