BUGFIX: Update bug in assets

There are 2 Bugs fixed by this:

1) Navigating to a subfolder, then navigating to pages then clicking on "Files" in the CMS Menu results in opening the previously opened subfolder instead (as expected and probably intended) the root folder.

2) Navigating to the first level after root and using the browser - Back - Button thereafter results in the url changing from /assets/show/1 to /assets/ however, nothing happens as there is no update triggered. This is a very serious bug, as it is expected by the user that something happens because the back button works in all other circumstances inside the CMS