Fixed linter errors

.eslintrc.json

@@ -9,6 +9,7 @@
     "no-unused-vars": ["error", {"varsIgnorePattern": "utils"}]
   },
   "globals": {
+    "nw": true,
     "utils": true
   }
 }

app/about.html

@@ -13,7 +13,7 @@
     <div id="main-event">
         <div class="content">
             <h1>Boats Animator</h1>
-            <h2><span id="app-version"></span></h2>
+            <h2 id="app-version">Version</h2>
             <p>Boats Animator is a free cross-platform stop motion animation program created using HTML5, JavaScript, and WebRTC. Want to help out? <a href="#" onclick="utils.openURL('https://github.com/BoatsAreRockable/animator/issues')">Report any issues</a> you come across or <a href="#" onclick="utils.openURL('https://github.com/BoatsAreRockable/animator/blob/master/CONTRIBUTING.md')">contribute code</a>!</p>
             <button onclick="utils.openURL('https://github.com/BoatsAreRockable/animator/blob/master/LICENSE')"><i class="fa fa-legal"></i><span>License</span></button>
             <button onclick="utils.openURL('https://github.com/BoatsAreRockable/animator/graphs/contributors')"><i class="fa fa-list-ul"></i><span>Credits</span></button>

app/js/utils.js

@@ -1,8 +1,6 @@
 const utils = (function() {
   "use strict";
 
-  const win = nw.Window.get();
-
   /**
    * Open a URL in the user's browser.
    *