Remove debug statement containing access_token

The removed statement was logging the following message:

    GET url: https://api.foursquare.com/v2/users/self/checkins?oauth_token=XXXXXXXXXXXXXXXXXXXXXX&v=20130402 headers:{} data:

Logging sensitive user credentials (in this case OAuth v2 access token) is dangerous
Merge pull request #20 from ahmetalpbalkan/patch-1

Remove debug statement containing access_token