Hi! I've seen your requirements, I m interested in it, I have highest reviews for jQuery (frontend) at freelancer.com and have good completion rate, and experts in PHP(cakephp,CI,Zend) for Server side, expert in integrating (SOAP and RESTFul API) 3rd Party APIs .
I've not reviewed that fitbit API yet, I can check it once u reply back, let me know if u r interested