title: Upgrading to XCode 4.5.1 not possible
body: <p>I cannot download XCode 4.5.1 from the app store. I've a valid developer license and so on. I entered my Apple Id to login to the app store and after clicking on the Upgrade button for updating xcode 4.5.1 the button's text switches from "Upgrade" to "Install". But when clicking again on install nothing happens. So the situtation I'm ending up with is that I can click on the Install button but nothing ever happens...</p>
  
  <p>Currently I'm running XCode Version 4.4 (4F250) on my Mac OS Lion Version 10.7.5.</p>