Apply contribution guidelines to "AbstractSearcher"

Refactor `AbstractSearcher` class and its children. Also most of the
unnecessary logic that was on `AbstractSearcher` was put back into `In`
class.

This commit also updates all "SubdivisionCode" rules.

The script used to create the classes can be found on:
https://gist.github.com/henriquemoody/ec404f994a87b18c7771

library/Exceptions/SubdivisionCode/SaSubdivisionCodeException.php

@@ -16,12 +16,17 @@ namespace Respect\Validation\Exceptions\SubdivisionCode;
 use Respect\Validation\Exceptions\SubdivisionCodeException;
 
 /**
- * Exception class for Saudi Arabia subdivision code.
+ * Exception class for subdivision codes of Saudi Arabia.
  *
  * ISO 3166-1 alpha-2: SA
+ *
+ * @author Henrique Moody <henriquemoody@gmail.com>
  */
-class SaSubdivisionCodeException extends SubdivisionCodeException
+final class SaSubdivisionCodeException extends SubdivisionCodeException
 {
+    /**
+     * {@inheritdoc}
+     */
     public static $defaultTemplates = [
         self::MODE_DEFAULT => [
             self::STANDARD => '{{name}} must be a subdivision code of Saudi Arabia',