sorted root entities by name (not case sensitive).

Couldn't find existing code that sorted entity headers, so just passed a simple comparator to Collections.sort.
Please pull out the same code in HomePresenter.getChallengeProjectHeaders() into a new method.  
You could run that new method in HomePresenter before handing the entity headers to the entitytreebrowser, and remove sort from entitytreebrowser.  Alternatively, you can deal with the sort in the EntityTreeBrowser presenter (and test it there).  Sorting the collection should not take place in the view.