Some trivial enhancements for IDE autocompletion and hinting

Hi! I've added a proper static factory and corrected the @result of Money::distribute so that IDEs (PhpStorm) can understand the code better.

$fiveEur = MoneyFactory::EUR(500);
$tenEur = $fiveEur->add($fiveEur); //IDE recognizes $tenEur as a Money instance
$parts = $tenEur->allocate(array(1, 1, 1));
$parts[0]->//(IDE here now suggests correctly)