Fix #4: Lazily evaluate published_on default value
Fix #4: Lazily evaluate published_on default value

feincms/feincms-elephantblog,joshuajonah/feincms-elephantblog,matthiask/feincms-elephantblog,joshuajonah/feincms-elephantblog,feincms/feincms-elephantblog,sbaechler/feincms-elephantblog,michaelkuty/feincms-elephantblog,michaelkuty/feincms-elephantblog,sbaechler/feincms-elephantblog,joshuajonah/feincms-elephantblog,michaelkuty/feincms-elephantblog,matthiask/feincms-elephantblog,sbaechler/feincms-elephantblog,matthiask/feincms-elephantblog