Update Foursquare in Readme.
Update Foursquare in Readme.

calebd/SimpleAuth,hoanganh6491/SimpleAuth,tipbit/SimpleAuth,hyperspacemark/SimpleAuth,adamjmcgrath/SimpleAuth-1,sburavtsov/SimpleAuth,martinpilch/SimpleAuth,tofaruk/SimpleAuth-1,jiakai-lian/SimpleAuth,machelix/SimpleAuth,AlexanderMazaletskiy/SimpleAuth