Change Config::load() process

Change to check whether each array are assoc or not.
As a result of this change, the following settings can be.

```php
\Config::load(array(
	'test' => array(
		'foo' => 'bar',
		'fuel' => 'php',
		'multi' => array(
			'key' => 'value',
			'numbers' => array(1, 2),
		),
		'array' => array(1, 2, 3),
	)
));

\Config::load(array(
	'test' => array(
		'foo' => 'boo',
		'multi' => array(
			'numbers' => array(),
		),
		'array' => array(1, 9),
	)
));

print_r(\Config::get('test'));

// Array
// (
//     [foo] => boo
//     [fuel] => php
//     [multi] => Array
//         (
//             [key] => value
//             [numbers] => Array
//                 (
//                 )
//         )
//     [array] => Array
//         (
//             [0] => 1
//             [1] => 9
//         )
// )
```