Update CHANGELOG in preparation for 0.7.2
Update CHANGELOG in preparation for 0.7.2

Summary: Closes https://github.com/facebook/relay/pull/903

Differential Revision: D3011262

Pulled By: steveluscher

fb-gh-sync-id: 4b9c112ad085964447091e72f1c87e6f1ffa2574
shipit-source-id: 4b9c112ad085964447091e72f1c87e6f1ffa2574

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