Values should accept bytes as valid string output

ethutil/value.go

@@ -98,6 +98,8 @@ func (val *Value) Str() string {
 		return string(a)
 	} else if a, ok := val.Val.(string); ok {
 		return a
+	} else if a, ok := val.Val.(byte); ok {
+		return string(a)
 	}
 
 	return ""