cmd/util: lowered default gas price

cmd/utils/flags.go

@@ -154,7 +154,7 @@ var (
 	GasPriceFlag = cli.StringFlag{
 		Name:  "gasprice",
 		Usage: "Sets the minimal gasprice when mining transactions",
-		Value: new(big.Int).Mul(big.NewInt(1), common.Szabo).String(),
+		Value: new(big.Int).Mul(big.NewInt(500), common.Shannon).String(),
 	}
 
 	UnlockedAccountFlag = cli.StringFlag{