Update README with link to Passport-Fitbit.
Update README with link to Passport-Fitbit.

Rosmina/createAccount,qitianchan/passport,kolomiichenko/passport,1602/passport,mcanthony/passport,kidaa/passport,modulexcite/passport,shubham13jain/passport,DaAwesomeP/passport,jameswomack/passport-restify,bevacqua/passport,wakashige/passport,Faiz7412/passport,jaredhanson/passport,arover/passport,bartuspan/passport,Trult/passport,imjerrybao/passport,dentrinh/passport,mjhea0/passport,ernestopino/passport,pandeysoni/passport