Procfile: use grpc-proxy instead of v2 proxy
Procfile: use grpc-proxy instead of v2 proxy

Signed-off-by: Gyu-Ho Lee <3454051ee3341eb69bdf6fca40899cdad4d86496@gmail.com>

ajityagaty/etcd,gyuho/etcd,mqliang/etcd,dannysauer/etcd,mqliang/etcd,visheshnp/etcd,joshix/etcd,heyitsanthony/etcd,bdarnell/etcd,vimalk78/etcd,rnaveiras/etcd,gyuho/etcd,bdarnell/etcd,vimalk78/etcd,fanminshi/etcd,cockroachdb/etcd,whuwxl/etcd,whuwxl/etcd,fanminshi/etcd,etcd-io/etcd,mkumatag/etcd,xiang90/etcd,YuleiXiao/etcd,etcd-io/etcd,cockroachdb/etcd,li-ang/etcd,glevand/coreos--etcd,glevand/coreos--etcd,etcd-io/etcd,coreos/etcd,rnaveiras/etcd,akauppi/etcd,visheshnp/etcd,ajityagaty/etcd,lorneli/etcd,YuleiXiao/etcd,mkumatag/etcd,sebrandon1/etcd,sinsharat/etcd,rnaveiras/etcd,bluebreezecf/etcd,mqliang/etcd,dannysauer/etcd,joshix/etcd,lorneli/etcd,ajityagaty/etcd,akauppi/etcd,li-ang/etcd,sebrandon1/etcd,mkumatag/etcd,sinsharat/etcd,coreos/etcd,xiang90/etcd,heyitsanthony/etcd,bluebreezecf/etcd