auto-focus primary button in "delete route" dialog (#387)

After opening the "delete route" dialog the primary action button gets the
current focus. So it's possible to confirm resetting the route by pressing
"Enter".

bootbox had to be updated to to achieve this (in prior versions of bootbox the
needed callback didn't exist).

see #385

js/index.js

@@ -153,6 +153,9 @@
                     },
                 ],
                 value: ['route'],
+                onShown: function () {
+                    $('button.bootbox-accept', $(this)).focus();
+                },
                 callback: function (result) {
                     if (result !== null) {
                         if (result.indexOf('route') !== -1) {