etcdserver: handle incoming v3 snapshot correctly
etcdserver: handle incoming v3 snapshot correctly

1. we should update all kv reference (including the
on in snapStore).

2. we should first restore a new KV and then close
the old one asynchronously.

CrazyJvm/etcd,sebrandon1/etcd,chipironcin/etcd,handsomesun/etcd,fanminshi/etcd,bdarnell/etcd,fasaxc/etcd,shawnps/etcd,jonboulle/etcd,endocode/etcd,wantonsolutions/dinv-etcd,purpleidea/etcd,cockroachdb/etcd,visheshnp/etcd,dannysauer/etcd,whuwxl/etcd,joshix/etcd,endocode/etcd,westhood/etcd,ravigadde/etcd,nekto0n/etcd,cchamplin/etcd,YuleiXiao/etcd,chipironcin/etcd,ktateish/etcd,akauppi/etcd,rnaveiras/etcd,sayden/etcd,swingbach/etcd,YuleiXiao/etcd,sebrandon1/etcd,glevand/coreos--etcd,yudai/etcd,zaphod-concur/etcd,sofuture/etcd,tguangch/etcd,glevand/coreos--etcd,fasaxc/etcd,ravigadde/etcd,cockroachdb/etcd,linuxcer/etcd,Timer/etcd,tguangch/etcd,rchicoli/etcd,coreos/etcd,westhood/etcd,gyuho/etcd,qqsun8819/etcd,heyitsanthony/etcd,li-ang/etcd,glycerine/etcd,armstrongli/etcd,coreos/etcd,plasticbox/etcd,swingbach/etcd,gyuho/etcd,xiang90/etcd,mqliang/etcd,oscarrr110/etcd,etcd-io/etcd,ajityagaty/etcd,siddontang/etcd,lorneli/etcd,purpleidea/etcd,wantonsolutions/dinv-etcd,OyTao/etcd_learning,mkumatag/etcd,tamird/etcd,ajityagaty/etcd,rchicoli/etcd,achanda/etcd,vimalk78/etcd,rnaveiras/etcd,lumjjb/etcd,siddontang/etcd,shawnps/etcd,bdarnell/etcd,CrazyJvm/etcd,mkumatag/etcd,StorReduce/etcd,mickep76/etcd,jlamillan/etcd,visheshnp/etcd,tamird/etcd,oscarrr110/etcd,dnaeon/etcd,mickep76/etcd,heyitsanthony/etcd,hongchaodeng/etcd,sofuture/etcd,cchamplin/etcd,jonboulle/etcd,dannysauer/etcd,luxas/etcd,Timer/etcd,handsomesun/etcd,qqsun8819/etcd,mqliang/etcd,raoofm/etcd,sinsharat/etcd,sayden/etcd,plasticbox/etcd,a-robinson/etcd,OyTao/etcd_learning,insequent/etcd,joshix/etcd,insequent/etcd,ktateish/etcd,whuwxl/etcd,lorneli/etcd,mkumatag/etcd,linuxcer/etcd,armstrongli/etcd,lumjjb/etcd,nekto0n/etcd,luxas/etcd,xiang90/etcd,akauppi/etcd,ajityagaty/etcd,achanda/etcd,sinsharat/etcd,wantonsolutions/dinv-etcd,raoofm/etcd,hongchaodeng/etcd,rnaveiras/etcd,etcd-io/etcd,li-ang/etcd,jlamillan/etcd,fanminshi/etcd,fasaxc/etcd,yudai/etcd,vimalk78/etcd,mqliang/etcd,glycerine/etcd,bluebreezecf/etcd,a-robinson/etcd,StorReduce/etcd,bluebreezecf/etcd,etcd-io/etcd,zaphod-concur/etcd,dnaeon/etcd