[BUG #8417] always add pages to container
[BUG #8417] fixed bottom border for active tab
[BUG #8417] make sure there's always an opened page in horizontal mode
[BUG #8417] fixed styles for justified alignment in IE9
[BUG #8417] ensure buttons always have the right class
[BUG #8417] fixed styles for right and left alignment in IE9
[BUG #8417] merged CSS classes for accordion and tabs