MRBS 1.12.2 等保2.0二级整改完整提交

包含：登录失败锁定、90天密码有效期、30分钟会话超时、
强制改密、登录审计日志、屏幕水印、企业背景图、
备案信息固定底部、favicon、JS空集合保护、
会话过期体验优化（403 JSON）、display_errors 关闭、
固定 key 根治 Integrity check failed 等全部改动

注意：config.inc.php/.htaccess/.user.ini 含敏感信息，
通过 .gitignore 排除，勿推送到公开仓库。

lib/Psr/Log/NullLogger.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace Psr\Log;
+
+/**
+ * This Logger can be used to avoid conditional log calls.
+ *
+ * Logging should always be optional, and if no logger is provided to your
+ * library creating a NullLogger instance to have something to throw logs at
+ * is a good way to avoid littering your code with `if ($this->logger) { }`
+ * blocks.
+ */
+class NullLogger extends AbstractLogger
+{
+    /**
+     * Logs with an arbitrary level.
+     *
+     * @param mixed  $level
+     * @param string $message
+     * @param array  $context
+     *
+     * @return void
+     *
+     * @throws \Psr\Log\InvalidArgumentException
+     */
+    public function log($level, $message, array $context = array())
+    {
+        // noop
+    }
+}