client.go
func NewRClient(host string, port int64) (RClient, error) {
	return NewRClientWithAuth(host, port, "", "")
}
func NewRClient(host string, port int64) (RClient, error) {
	return NewRClientWithAuth(host, port, "", "")
}
// NewRClient creates a RClient which will run commands on the RServe server located at the provided host and port