Set required celery version 3.1
Set required celery version 3.1

ChinaQuants/flower,allengaller/flower,tellapart/flower,tellapart/flower,lucius-feng/flower,raphaelmerx/flower,pygeek/flower,asmodehn/flower,alexmojaki/flower,ucb-bar/bar-crawl-web,lucius-feng/flower,marrybird/flower,asmodehn/flower,ucb-bar/bar-crawl-web,Lingling7/flower,alexmojaki/flower,allengaller/flower,raphaelmerx/flower,marrybird/flower,ChinaQuants/flower,jzhou77/flower,Lingling7/flower,Lingling7/flower,asmodehn/flower,pj/flower,barseghyanartur/flower,marrybird/flower,alexmojaki/flower,raphaelmerx/flower,lucius-feng/flower,pygeek/flower,pj/flower,ChinaQuants/flower,jzhou77/flower,allengaller/flower,barseghyanartur/flower,barseghyanartur/flower,ucb-bar/bar-crawl-web,pygeek/flower,jzhou77/flower,pj/flower,tellapart/flower