Fix application icon for Windows and Linux

See #85

src/main.js

@@ -117,7 +117,9 @@ app.on('ready', function() {
     // follow Electron's defaults
     window_options = {};
   }
-  window_options.icon = path.resolve(__dirname, 'resources/appicon.png');
+  if (process.platform === 'linux') {
+    window_options.icon = path.resolve(__dirname, 'resources/appicon.png');
+  }
   window_options.fullScreenable = true;
   mainWindow = new BrowserWindow(window_options);
   mainWindow.setFullScreenable(true); // fullscreenable option has no effect.