Creates GPX tracks for all strava activities of a user. Uses streams api v3 to reconstruct the uploaded tracks.

1. Checkout repo
2. Call www.strava.com/oauth/authorize?client_id=1924&response_type=code&redirect_uri=http://localhost/exchange_token&approval_prompt=force&scope=view_private in your browser.
3. Copy the value of 'code' from the response and insert it in a file named 'access_token.txt' directly in the checked out repo
4. Call strava.rb

Reconstructed GPX tracks from all your activities will be placed in the current directory. Due to the restrictions of the strava V3 api these is not your original uploaded gpx file. It is reconstructed from so called streams, see: https://strava.github.io/api/v3/streams/

The created GPX files are named by the name of the original uploaded file -- if the activity was uploaded via the strava app this is a woozily hash -- and the start date and time of the activity.