[TASK] Adjust design to new guidelines (refs #392)
[FEATURE] Make upload due date configurable (refs #392)
[TASK] Improve UX of column assignment (refs #392)
[TASK] Make column salutation non-mandatory (refs #392)
[FEATURE] Allow setting firstrowColumnnames on re-assigning columns (refs #392)
[FEATURE] Save businessuser in address, save number of imported addresses in dataset, statistics module (refs #392)
[FEATURE] Allow using the last imported address data for a new votingDay (refs #392)