remove DateHelper
remove DateHelper

DateHelper is no longer necessary here as it is called in the getCollectionDatePublic() already.

Former-commit-id: 43442785c67ce1c70d192306f05962e55d9b0b67
MrKarlDilkington/concrete5,jaromirdalecky/concrete5,acliss19xx/concrete5,haeflimi/concrete5,concrete5/concrete5,acliss19xx/concrete5,biplobice/concrete5,mainio/concrete5,rikzuiderlicht/concrete5,biplobice/concrete5,jaromirdalecky/concrete5,acliss19xx/concrete5,olsgreen/concrete5,triplei/concrete5-8,rikzuiderlicht/concrete5,a3020/concrete5,a3020/concrete5,haeflimi/concrete5,KorvinSzanto/concrete5,concrete5/concrete5,triplei/concrete5-8,concrete5/concrete5,hissy/concrete5,haeflimi/concrete5,KorvinSzanto/concrete5,mlocati/concrete5,mlocati/concrete5,biplobice/concrete5,deek87/concrete5,mlocati/concrete5,rikzuiderlicht/concrete5,biplobice/concrete5,deek87/concrete5,deek87/concrete5,mainio/concrete5,hissy/concrete5,MrKarlDilkington/concrete5,MrKarlDilkington/concrete5,deek87/concrete5,jaromirdalecky/concrete5,hissy/concrete5,hissy/concrete5,mainio/concrete5,concrete5/concrete5,mlocati/concrete5,jaromirdalecky/concrete5,olsgreen/concrete5,KorvinSzanto/concrete5,olsgreen/concrete5,haeflimi/concrete5,triplei/concrete5-8