Update Jest to 12.1
Update Jest to 12.1

Summary:
https://github.com/facebook/jest/blob/master/CHANGELOG.md
Closes https://github.com/facebook/relay/pull/1157

Differential Revision: D3330011

Pulled By: cpojer

fbshipit-source-id: f42c76479da83041f309115f9239b74f5db9da99

atxwebs/relay,yungsters/relay,iamchenxin/relay,chirag04/relay,yungsters/relay,xuorig/relay,facebook/relay,atxwebs/relay,zpao/relay,kassens/relay,freiksenet/relay,facebook/relay,josephsavona/relay,josephsavona/relay,chentsulin/relay,gabelevi/relay,wincent/relay,facebook/relay,rosskevin/relay,voideanvalue/relay,gabelevi/relay,wincent/relay,chirag04/relay,facebook/relay,kassens/relay,rosskevin/relay,voideanvalue/relay,voideanvalue/relay,dbslone/relay,zpao/relay,wincent/relay,dbslone/relay,wincent/relay,cpojer/relay,benjaminogles/relay,cpojer/relay,xuorig/relay,cpojer/relay,benjaminogles/relay,voideanvalue/relay,chentsulin/relay,kassens/relay,voideanvalue/relay,freiksenet/relay,facebook/relay,zpao/relay,xuorig/relay,cpojer/relay,facebook/relay,freiksenet/relay,apalm/relay,atxwebs/relay,atxwebs/relay,apalm/relay,chirag04/relay,josephsavona/relay,iamchenxin/relay,iamchenxin/relay,benjaminogles/relay,kassens/relay,yungsters/relay,kassens/relay,xuorig/relay,wincent/relay,gabelevi/relay,kassens/relay,voideanvalue/relay,iamchenxin/relay,xuorig/relay,wincent/relay,apalm/relay,xuorig/relay,chentsulin/relay