[feature/passwords] Add salted md5 (phpBB3 default) and phpass drivers

The phpass driver extends the standard salted md5 driver of phpBB3. It will
only support the $P$ prefix that phpass uses.

PHPBB3-11610

phpBB/includes/crypto/driver/phpass.php

@@ -0,0 +1,40 @@
+<?php
+/**
+*
+* @package phpBB3
+* @copyright (c) 2013 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* @package crypto
+*/
+class phpbb_crypto_driver_phpass extends phpbb_crypto_driver_salted_md5
+{
+	const PREFIX = '$P$';
+
+	/**
+	* @inheritdoc
+	*/
+	public function get_prefix()
+	{
+		return self::PREFIX;
+	}
+
+	/**
+	* @inheritdoc
+	*/
+	public function get_type()
+	{
+		return get_class($this);
+	}
+}