functional-tester/rpcpb: support extra dial options
functional-tester/rpcpb: support extra dial options

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

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