Fix tslint errors for all addons and un-exclude tests for search addon

src/addons/search/search.test.ts

@@ -2,6 +2,7 @@
  * Copyright (c) 2018 The xterm.js authors. All rights reserved.
  * @license MIT
  */
+declare var require: any;
 
 import { assert, expect } from 'chai';
 import * as search from './search';

src/addons/search/tsconfig.json

@@ -18,8 +18,5 @@
   },
   "include": [
     "**/*.ts"
-  ],
-  "exclude": [
-    "**/*.test.ts"
   ]
 }