Allow delegates to be called with parameters.

Not sure if useful. This was kind of a knee-jerk modification, and there may be a better way of doing it already (like supplying a closure for the factory method), so feel free to reject this pull if you feel this doesn't fit.

I made the changes because I often see factories used like:

    $db = DatabaseFactory::getAdapter('MySQL', $options);

The change would allow delegates to be used like:

    $injector->delegate('Database', 'DatabaseFactory', [':adapter' => 'MySQL', 'options' => $options]);
    $injector->make('Database');