weights should be float64, add food log

* Fix: weights should be float64 (#8)

* Update: retrieve food log

update and fix BreathingRateTimePoint::DateTime type (it contains onl…

…y the date)

add AllActivityTypes method

Update public API, create v2 (#6)

Fix OxygenSaturation return type. DateTime -> Date

SleepLog: fix date-time types

Remove duplicated HeartRateZones. Fix UserHeartRateTimeseries. Update

update deps and complete decouple from storage