fixes Foursquare versioning bug

Hi,

From Foursquare documentation:
`As of January 28, 2014, requests that do not include a  v parameter will be rejected.`

I didn't see that one coming, so I updated the provider in order for it to work. :)

Also, any news on issue #17? Have you got any plan for the implementation of SSO providers? (Facebook, etc.)

Thanks,
Julien