Fix incorrect counting of coffees made during time close to midnight

Fix incorrect counting of coffees made during time close to midnight

Datetime in database is stored in UTC timezone. Currently we are in
UTC +2 timezone (GMT +1). Because of time shifts fixing the time
cannot be done in a static way.

Dynamic solution is using paramater 'localtime' in SQL query function
date(). Therefore it is required for the target device to have
properly set timezone.

TODO:
Suggested solution is to use 'type converters' for python/sqlite3.