startOf now support isoWeek
startOf now support isoWeek

As requested by #855

joelmheim/moment,Jeremy017/moment,umurkontaci/moment,rawbenny/moment,xkxx/moment,deskfed/moment,jisaacks/moment,samuelfullerthomas/moment,hitesh97/moment,StevenHeinrich/moment,umurkontaci/moment,edivancamargo/moment,opdude/moment,npmcomponent/moment-moment,joelmukuthu/moment,yashanet/moment,evilemon/moment,mcanthony/moment,wangjun/moment,mj1856/moment,Oire/moment,daviYang/moment,hhariri/moment,timothyfstephens/moment,opdude/moment,keigoleung/moment,fdegiuli/moment,wesleifreitas/moment,giobero999/moment,deepakrohan1/moment,GerHobbelt/moment,jeanmatheussouto/moment,OtkurBiz/moment,marijaselakovic/moment,Oiro/moment,optimizely/moment,6ft-invsbl-rbbt/moment,BlueSky1021/moment,digitalavenueslimited/moment,mcanthony/moment,scriptrdotio/moment,xkxx/moment,6ft-invsbl-rbbt/moment,joelmheim/moment,mathiasrw/moment,iamstarkov/moment,Aliccer/moment,vnathalye/moment,massic80/moment,massic80/moment,gabrielmaldi/moment,gtanner/moment,oss-practice/moment,bamatraf/moment,CapeSepias/moment,shuai959980629/moment,supriyantomaftuh/moment,giobero999/moment,zhil/moment,baiyanghese/moment,rento41/moment,topaxi/moment,dramalho/moment,StevenHeinrich/moment,lucidogen/moment,whytobe/moment,ichernev/moment,kidaa/moment,dardrone/moment,petrbela/moment,evilemon/moment,mhijazi1/moment,trungnghia112/moment,1ec5/moment,monoblaine/moment,rento41/moment,Acquisio/moment,d0rc/moment,hhariri/moment,mj1856/moment,maggiepint/moment,supriyantomaftuh/moment,dramalho/moment,topaxi/moment,moment/moment,PKRoma/moment,davidyen1124/moment,etodd/moment,bici-zhuguangzu/moment,nikolas/moment,jaiminmoslake7020/moment,raphamorim/moment,syntheticgoo/moment,jawish/moment,AladdinSonni/moment,ichernev/moment,hitesh97/moment,bamatraf/moment,lucidogen/moment,nikolas/moment,treyhunner/moment,nonmadden/moment,fdegiuli/moment,kimjji/moment,jaiminmoslake7020/moment,OtkurBiz/moment,mathiasrw/moment,joelmukuthu/moment,samuelfullerthomas/moment,djheart0710/moment,sonicparke/moment,PaulinePro/moment,IveWong/moment,mcauser/moment,ebabel-eu/moment,OtkurBiz/moment,j6k4m8/moment,kepta/moment,suxuekun/moment,abbasmhd/moment,petkaantonov/moment,vnathalye/moment,deepakrohan1/moment,prabhu5013/moment,shuai959980629/moment,monoblaine/moment,moment/moment,maggiepint/moment,ze-pequeno/moment,DH0/moment,sigurdga/moment,mcauser/moment,julionc/moment,edivancamargo/moment,BookingBug/moment,SkReD/moment,timothyfstephens/moment,Oire/moment,gtanner/moment,PKRoma/moment,xiebaochun/moment,iamstarkov/moment,daviYang/moment,ze-pequeno/moment,grigorkh/moment,Oire/moment,Aliccer/moment,djheart0710/moment,julionc/moment,billybonz1/moment,IveWong/moment,Khamull/moment,ThiagoGarciaAlves/moment,marijaselakovic/moment,kevinrodbe/moment,wangjun/moment,samuelfullerthomas/moment,sigurdga/moment,BlueSky1021/moment,bbc/moment,bici-zhuguangzu/moment,G-Grand/moment,yblee85/moment,baiyanghese/moment,nonmadden/moment,xkxx/moment,calebcauthon/moment,calebcauthon/moment,davidyen1124/moment,GerHobbelt/moment,AladdinSonni/moment,timrwood/moment-es6,mj1856/moment,optimizely/moment,Brandon-Royal/moment,guanwanjun/moment,julionc/moment,yblee85/moment,mquandalle/moment,maggiepint/moment,thehungrycoder/moment,billybonz1/moment,digitalavenueslimited/moment,Khamull/moment,grigorkh/moment,poljeff/moment,BookingBug/moment,poljeff/moment,smnbbrv/moment,G-Grand/moment,kcthota/moment,d0rc/moment,ksnabb/moment,PKRoma/moment,mquandalle/moment,Khan/moment,nurlan/moment,jasonmendes/moment,Khan/moment,yashanet/moment,ducksboard/moment,syntheticgoo/moment,kepta/moment,dardrone/moment,rawbenny/moment,rollbar/moment,DH0/moment,jawish/moment,ebabel-eu/moment,keigoleung/moment,jasonmendes/moment,deskfed/moment,kcthota/moment,Jeremy017/moment,zhil/moment,scriptrdotio/moment,raphamorim/moment,gabrielmaldi/moment,joelmheim/moment,oss-practice/moment,PaulinePro/moment,guanwanjun/moment,trungnghia112/moment,smnbbrv/moment,wesleifreitas/moment,j6k4m8/moment,scriptrdotio/moment,thehungrycoder/moment,ksnabb/moment,CapeSepias/moment,kidaa/moment,kevinrodbe/moment,ze-pequeno/moment,mhijazi1/moment,jeanmatheussouto/moment,calebcauthon/moment,moment/moment,pietercolpaert/moment,treyhunner/moment,etodd/moment,suxuekun/moment,bbc/moment,Oiro/moment,ThiagoGarciaAlves/moment,prabhu5013/moment,whytobe/moment,sonicparke/moment,stoeffel/moment,Brandon-Royal/moment,nurlan/moment,abbasmhd/moment,xiebaochun/moment,kimjji/moment,pietercolpaert/moment,Acquisio/moment,jisaacks/moment,petrbela/moment,stoeffel/moment