Break out event handler setup into separate method

This mirrors the keymap setup method and allows specs
to reattach handlers after calling shutdown()

spec/app/window-spec.coffee

@@ -5,6 +5,7 @@ describe "Window", ->
   [rootView] = []
 
   beforeEach ->
+    window.setUpEventHandlers()
     window.attachRootView(require.resolve('fixtures'))
     rootView = window.rootView
 

src/app/window.coffee

@@ -25,7 +25,9 @@ windowAdditions =
     @syntax = new Syntax
     @setUpKeymap()
     @pasteboard = new Pasteboard
+    @setUpEventHandlers()
 
+  setUpEventHandlers: ->
     $(window).on 'core:close', => @close()
     $(window).command 'window:close', => @close()
     $(window).command 'window:toggle-full-screen', => atom.toggleFullScreen()