coinbase.go
func (c Client) SendMoney(params *TransactionParams) (*transactionConfirmation, error) {
	return c.transactionRequest("POST", "send_money", params)
}
func (c Client) SendMoney(params *TransactionParams) (*transactionConfirmation, error) {
	return c.transactionRequest("POST", "send_money", params)
}
// SendMoney to either a bitcoin or email address