bookmarks: make read later-button draggable again, fixes oc-944
bookmarks: make read later-button draggable again, fixes oc-944

owncloud/bookmarks,shtrom/bookmarks,shtrom/bookmarks,tflidd/bookmarks,behrisch/bookmarks,tflidd/bookmarks,behrisch/bookmarks,owncloud/bookmarks,alberanid/bookmarks,alberanid/bookmarks