Updated Fitbit Metrics

Fitbit has deprecated 'Activity Points' in favor of 'Active Minutes' (see: https://help.fitbit.com/customer/portal/articles/1122080). So we should log that instead.
Added logging of 'Calories Out' since I find that a useful metric.
Merge pull request #1 from rufusisnodufus/update-fitbit-metrics

Updated Fitbit Metrics