Added google-cli.py example based on a version from brunoqc, and added google flask example

I have done several things here:

* Added an old google-cli example, which has somehow disappeared (originally contributed by brunoqc)
* Modified that example: some bugfixes (maybe because based on an older version of rauth), and also added support for code/access selection: if the application has already been authorized, it will reply with an access_token, otherwise with a code
* Added a google flask example, based on the facebook flask example
* Created a secrets.py.template, which must be copied to secrets.py (excluded in .gitignore) and filled-in with the application specific secrets. Useful for testing. Maybe the other secrets can be moved here
* Modified the .gitignore, to reflect those decissions and also ignore emacs backup files (*~) and the database files (*.db)