Add back dialog require used for path prompting

Closes #1861

src/browser/atom-application.coffee

@@ -5,6 +5,7 @@ AutoUpdateManager = require './auto-update-manager'
 BrowserWindow = require 'browser-window'
 Menu = require 'menu'
 app = require 'app'
+dialog = require 'dialog'
 fs = require 'fs'
 ipc = require 'ipc'
 path = require 'path'