update user schema
add fitbit avatar to user document
find users by id and method to return json with all fitbit users
routes for getting json of all users and only fitbit users
Merge branch 'master' of https://github.com/Fittr/fittr
Merge branch 'master' of https://github.com/Fittr/fittr
Merge pull request #28 from sarchila/master

user schema and routes for getting json of all users and only fitbit users