próbowałem zostawić jquery 1.12 ale nic z tego.
<!-- start bootstrap -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js" integrity="sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa" crossorigin="anonymous"></script>
<!-- datatables -->
<link rel="stylesheet" href="//cdn.datatables.net/1.10.13/css/jquery.dataTables.min.css">
<script src="//code.jquery.com/jquery-1.12.4.js"></script>
<script src="//cdn.datatables.net/1.10.13/js/jquery.dataTables.min.js"></script>
<link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<link rel="stylesheet" href="https://cdn.datatables.net/1.10.13/css/dataTables.bootstrap.min.css">
<script src="https://cdn.datatables.net/1.10.13/js/dataTables.bootstrap.min.js"></script>
<!-- datatables -->
<script type="text/javascript" class="init">
$(document).ready(function() {
$('#wszyscy').DataTable( {
"order": [[ 0, "desc" ]]
} );
} );
<!-- start datepicker -->
<link href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/base/jquery-ui.css" rel="stylesheet" type="text/css"/>
<!--<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.5/jquery.min.js"></script> to jest zalecany jquery-->
<script src="//code.jquery.com/jquery-1.12.4.js"></script> <!-- tu ponownie go wrzuciłem 1.12 choć pewnie niepotrzebnie -->
<script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/jquery-ui.min.js"></script>
<script type="text/javascript">
$(function() {
$(".datepicker").datepicker({
dateFormat: "dd-mm-yy",
dayNamesMin: [ "nd", "pn", "wt", "śr", "cz", "pt", "sb" ],
monthNames: [ "Styczeń", "Luty", "Marzec", "Kwiecień", "Maj", "Czerwiec", "Lipiec", "Sierpień", "Wrzesień", "Październik", "Listopad", "Grudzień" ],
firstDay: 1 }).val()
});
</script>
<!-- koniec datepicker -->