added simple date format - a bit hackish
Revert "added simple date format - a bit hackish"

This reverts commit 1f75e7ebe30a5c84d0f734d8a074c86dec13b9bb.

ISO8601 format must be used.
Revert "Revert "added simple date format - a bit hackish""

This reverts commit 838c59d2b789d9df9ad7f07ca556b3b4e11bf63e.
don't create Calendars unnecessarily