issues #6406#6399
- all dates are stored as UTC with this commit
- use moment.tz.setDefault('UTC')
- add migration file to recalculate local datetimes to UTC
- store all dates in same format into our three supported databases
- add option to remeber migrations inside settings (core)
- support DST offset for migration
- ensure we force UTC in test env
- run whole migration as transaction
- extend: Settings.findOne function
