Added yappi to requirements_dev.txt.
Added yappi to requirements_dev.txt.

enigmampc/catalyst,humdings/zipline,bartosh/zipline,sketchytechky/zipline,grundgruen/zipline,iamkingmaker/zipline,semio/zipline,dhruvparamhans/zipline,erikness/AlephOne,Scapogo/zipline,morrisonwudi/zipline,dhruvparamhans/zipline,zhoulingjun/zipline,davidastephens/zipline,florentchandelier/zipline,gwulfs/zipline,StratsOn/zipline,euri10/zipline,michaeljohnbennett/zipline,kmather73/zipline,euri10/zipline,morrisonwudi/zipline,StratsOn/zipline,humdings/zipline,mattcaldwell/zipline,bartosh/zipline,dkushner/zipline,magne-max/zipline-ja,alphaBenj/zipline,umuzungu/zipline,chrjxj/zipline,MonoCloud/zipline,alphaBenj/zipline,stkubr/zipline,jimgoo/zipline-fork,stkubr/zipline,quantopian/zipline,wubr2000/zipline,CarterBain/AlephNull,ronalcc/zipline,jordancheah/zipline,CDSFinance/zipline,kmather73/zipline,florentchandelier/zipline,AlirezaShahabi/zipline,dmitriz/zipline,otmaneJai/Zipline,nborggren/zipline,enigmampc/catalyst,cmorgan/zipline,grundgruen/zipline,DVegaCapital/zipline,michaeljohnbennett/zipline,dkushner/zipline,aajtodd/zipline,chrjxj/zipline,umuzungu/zipline,dmitriz/zipline,otmaneJai/Zipline,CarterBain/AlephNull,joequant/zipline,magne-max/zipline-ja,gwulfs/zipline,semio/zipline,wilsonkichoi/zipline,zhoulingjun/zipline,jimgoo/zipline-fork,davidastephens/zipline,ChinaQuants/zipline,CDSFinance/zipline,wubr2000/zipline,nborggren/zipline,DVegaCapital/zipline,keir-rex/zipline,ronalcc/zipline,aajtodd/zipline,sketchytechky/zipline,iamkingmaker/zipline,MonoCloud/zipline,ChinaQuants/zipline,YuepengGuo/zipline,quantopian/zipline,keir-rex/zipline,AlirezaShahabi/zipline,cmorgan/zipline,wilsonkichoi/zipline,Scapogo/zipline,mattcaldwell/zipline,YuepengGuo/zipline,joequant/zipline,erikness/AlephOne,jordancheah/zipline