based on: https://stackoverflow.com/a/16870379/1596547
$('button span').parent().click(function () {
if($('button span').hasClass('glyphicon-chevron-down'))
{
$('button').html('<span class="glyphicon glyphicon-chevron-up"></span> Close');
}
else
{
$('button').html('<span class="glyphicon glyphicon-chevron-down"></span> Open');
}
});