Fixed missing os dependency

app/background.js

@@ -3,6 +3,7 @@
 // It doesn't have any windows which you can see on screen, but we can open
 // window from here.
 
+import os from 'os';
 import { app, BrowserWindow, ipcMain } from 'electron';
 import devHelper from './vendor/electron_boilerplate/dev_helper';
 import windowStateKeeper from './vendor/electron_boilerplate/window_state';
@@ -112,11 +113,11 @@ app.on('ready', function () {
     });
 
 	if(useToaster) {
-		
+
 	    toaster.init(mainWindow);
 
 		ipcMain.on('notification-shim', (e, msg) => {
-        
+
 			mainWindow.webContents.executeJavaScript(`
 				require('electron').ipcRenderer.send('electron-toaster-message', {
 					title: '${msg.title}',