Add a sample for how to connect to FitBit from a console app.

[AlexGhiondea]

The sample handles the authorization to FitBit and downloads the weight for the current day.

Once the app is authorized, the token data is stored locally to avoid having to re-authenticate every time. For brevity, the token is stored in plain text.

In order for the authorization to work it requires the app to be launched as admin. That is required in order for the app to be able to listen to the callback at 'http://localhost'. The app automatically handles this case.

[AlexGhiondea]

/cc @aarondcoleman @WestDiscGolf

[WestDiscGolf]

That's pretty cool! :)