We will currently only use the system time (instead of client time).
This tasks comprises of:

• Creating a filter that stores the System time in the TraitCollector
  • For now we'll use Date.class as key (event though using two dates will not be possible then, i.e. if one is interested in system & client time)
• A DateVoter with three properties
  • Date date
  • int duration
  • Enum durationType (hours, days, months)
• "Complex" Field with Datepicker + Select for DurationType + Numbered input for duration
  • Validator?
  • Transformer
• Package info.magnolia.p13n.date.system
• See JodaTime (http://www.joda.org/) for simplified date calculations