Drop JQuery-UI. Fixes Issue #353 partly

app/assets/javascripts/osem-datepickers.js

@@ -0,0 +1,34 @@
+$(function () {
+  $("#conference-start-datepicker").datetimepicker({
+      pickTime: false,
+      format: "YYYY-MM-DD"
+  });
+  $("#conference-end-datepicker").datetimepicker({
+      pickTime: false,
+      format: "YYYY-MM-DD"
+  });
+  $("#conference-reg-start-datepicker").datetimepicker({
+      format: "YYYY-MM-DD",
+      pickTime: false,
+      pickSeconds: false
+  });
+  $("#conference-reg-end-datepicker").datetimepicker({
+      format: "YYYY-MM-DD",
+      pickTime: false,
+      pickSeconds: false
+  });
+  $(".target-due-date-datepicker").datetimepicker({
+      pickTime: false,
+      format: "YYYY-MM-DD"
+  });
+  /* Appends the datetimepicker to new injected nested target fields. */
+  $('a:contains("Add target")').click(function () {
+      setTimeout(function () {
+          $('.target-due-date-datepicker').not('.hasDatepicker').datetimepicker({
+              pickTime: false,
+              format: "YYYY-MM-DD"
+          });
+      },
+      5)
+  });
+} );