update with new Foursquare logo!

replace old blue logo with sexy new logo as per [Foursquare logos](https://foursquare.com/about/logos) guide

![logo](http://media.tumblr.com/ffaf0075be879b3ab0b87f0b8bcc6814/tumblr_inline_n965bkOymr1qzxhga.png)