Add sorting to files list, trashbin and public files

apps/files/ajax/list.php

apps/files/css/files.css

apps/files/js/filelist.js

apps/files/lib/helper.php

apps/files/templates/index.php

apps/files/tests/js/filelistSpec.js

apps/files_sharing/ajax/list.php

apps/files_trashbin/ajax/list.php

apps/files_trashbin/lib/helper.php

apps/files_trashbin/templates/index.php