valid_from and valid_to attributes of schedule should consider in the time zone of the job or order to decide which schedule is active

Current Situation

• We assume that we have two schedules
  schedule1

  <schedule>
      <weekdays >
          <day  day="1 2 3 4 5 6 7">
              <period  single_start="01:00"/>
          </day>
      </weekdays>
  </schedule>
  

  schedule2

  <schedule  substitute="schedule1" valid_to="2017-03-14 21:00:00" valid_from="2017-03-14 19:00:00">
      <weekdays >
          <day  day="1 2 3 4 5 6 7">
              <period  single_start="20:00"/>
          </day>
      </weekdays>
  </schedule>
  

  where the second schedule substitutes the first in the specified date range (valid_from and valid_to)

• the next start time of a job or an order which used schedule1 is calculated with 20:00h on 2017-03-14 (after the run at 01:00)
• But when valid_from is reached then schedule2 is not marked as active
• It seems that the datetimes are used in UTC time zone to decide which scheduler is active.
• For example we assume that the time zone is Europe/Berlin then the above second schedule goes active at 2017-03-14 20:47:00 but 19:47:00 is expected.

Desired Behavior

The datetimes in valid_from and valid_to should use in the time zone of the job or order to decide which scheduler is active.

Maintainer Note

• The schedule uses the time zone of the order or job where it is assigned.
• If a schedule is used by two orders or jobs which have different time zones then which time zone should be uses to mark the substituted schedule as active?
  It is not possible.