always show app navigation scrollbar when too many apps in there
prevent shift of app titles caused by scrollbar
prevent shift of app names caused by scrollbar, part 2
fix navbar
Fix for IE - an ugly horizontal scrollbar appears

 * for IE9 the nav bar was too narrow
 * for other IEs the width of each app element was to wide and
   cause the horizontal scoll bar - now this content is hidden like
   before this PR
Merge pull request #5984 from owncloud/nav-scrollbar

always show app navigation scrollbar when too many apps in there