fix(datepicker): add custom class to year picker
fix(datepicker): add custom class to year picker

* add missing custom class to year picker

Closes #4558
Fixes #4546

matteopic/bootstrap,byronigoe/bootstrap,davious/angular-ui-bootstrap,deeg/bootstrap,wesleycho/bootstrap,icfantv/bootstrap,Servoy/bootstrap,angular-ui/bootstrap,realityking/ui-bootstrap,pdsoftplan/bootstrap,realityking/ui-bootstrap,burlhock/bootstrap,Lincoln-xzc/angular-ui-bootstrap,Servoy/bootstrap,shiftagent/ui-bootstrap,looker/bootstrap,BookingBug/bootstrap,292388900/bootstrap,292388900/bootstrap,davious/angular-ui-bootstrap,BookingBug/bootstrap,connyay/bootstrap,shadowdaw/bootstrap,icfantv/bootstrap,infowrap/bootstrap,guaido79/bootstrap,shiftagent/ui-bootstrap,shootermv/bootstrap,benhalverson/bootstrap,filso/bootstrap,matteopic/bootstrap,vfiles/bootstrap,benhalverson/bootstrap,oliversalzburg/bootstrap,connyay/bootstrap,Lincoln-xzc/angular-ui-bootstrap,christor/bootstrap,RobJacobs/bootstrap,benhalverson/bootstrap,RobJacobs/bootstrap,caoruiy/bootstrap,byronigoe/bootstrap,oliversalzburg/bootstrap,filso/bootstrap,deeg/bootstrap,Kpler/bootstrap,angular-ui/bootstrap,Kpler/bootstrap,caoruiy/bootstrap,pdsoftplan/bootstrap,wesleycho/bootstrap,Foxandxss/bootstrap,burlhock/bootstrap,sullivanpt/bootstrap,SystemDisc/bootstrap,justin-john/bootstrap-1,mabi/bootstrap,shadowdaw/bootstrap,christor/bootstrap,benhalverson/bootstrap,looker/bootstrap,tmcgee123/bootstrap,shootermv/bootstrap,tmcgee123/bootstrap,infowrap/bootstrap,fpipita/bootstrap,justin-john/bootstrap-1,mabi/bootstrap,SystemDisc/bootstrap,fpipita/bootstrap,Foxandxss/bootstrap,vfiles/bootstrap,sullivanpt/bootstrap,guaido79/bootstrap