1. Check the TODOs
2. Complete the challenges functionality.
3. Fix the Utils->getUserActivitiesByTimeForDateRange, it parses the string and constructs the object
4. Update the users personalStats : Need to implement service for body weight and body fat %
5. Utils->getUserActivitiesByTimeForDateRange and Utils-->GetAllTimeHighs do the same thing almost, need to extract out to a function
6. Send back some more personal stats like, longest run, most time in gym etc (with getAllTimeHighs).