add uninstall

uninstall.php

@@ -0,0 +1,15 @@
+<?php
+//防止有人恶意访问此文件，所以在没有 WP_UNINSTALL_PLUGIN 常量的情况下结束程序
+if( !defined( 'WP_UNINSTALL_PLUGIN' ) ) exit();
+
+$obs_options = get_option('oss_options', true);
+$upload_url_path = get_option('upload_url_path');
+$obs_upload_url_path = esc_attr($obs_options['upload_url_path']);
+
+//如果现在使用的是OSS的URL，则恢复原状
+if( $upload_url_path == $obs_upload_url_path ) {
+	update_option('upload_url_path', "" );
+}
+
+//移除配置
+delete_option('oss_options');