Forked drewjoh / phpPayPal added MassPay support

[uWebTech]

Added MassPay to this excellent class. Example use:
$paypal['api_username'] = 'username';
$paypal['api_password'] = 'password';
$paypal['api_signature'] = 'API';
// Initiate
$payment = new phpPayPal($paypal, true);
// Server (Required)
$payment->ip_address = $_SERVER['REMOTE_ADDR'];
$payment->add_mass_pay('test1@gmail.com', '5.00','uniqueid','a note for you and client');
$payment->add_mass_pay('test@yahoo.com', '5.00');
$payment->mass_pay();
if($payment->_error){
echo 'Error:
';
$payment->_error_long_message;
} else {
echo 'Success';
}