Make the docs a bit more user friendly [#70840170]

- I've tried to break this down into sections that explain the files a bit more explicitly
- possible TODO: Move the google auth flow stuff to it's own section
- renamed the `generate_credentials` file to `generate-ga-credentials.py` as it is specific to google analytics
I got an invalid client error - adding a name and support email under the ""APIs & auth" -> "Consent screen"" fixed this, may be worth noting

http://stackoverflow.com/questions/18677244/error-invalid-client-no-application-name