Pass app version via window's url.

We could save the sync message of atom.getVersion().

src/atom.coffee

@@ -104,7 +104,7 @@ class Atom extends Model
 
   # Private: Get the version of the Atom application.
   @getVersion: ->
-    @version ?= app.getVersion()
+    @version ?= @getLoadSettings().appVersion
 
   # Private: Determine whether the current version is an official release.
   @isReleasedVersion: ->

src/browser/atom-window.coffee

@@ -1,6 +1,7 @@
 BrowserWindow = require 'browser-window'
 Menu = require 'menu'
 ContextMenu = require './context-menu'
+app = require 'app'
 dialog = require 'dialog'
 ipc = require 'ipc'
 path = require 'path'
@@ -32,6 +33,7 @@ class AtomWindow
 
     loadSettings = _.extend({}, settings)
     loadSettings.windowState ?= '{}'
+    loadSettings.appVersion = app.getVersion()
 
     # Only send to the first non-spec window created
     if @constructor.includeShellLoadTime and not @isSpec