Fix bootstrap slider

Author: Dmitry Kuzin (DevExpress)

src/bootstrap-slider.js

@@ -34,6 +34,8 @@ function init(Survey) {
       });
     },
     afterRender: function(question, el) {
+      el.style.paddingTop = '20px';
+      el.style.paddingBottom = '17px';
       var inputEl = document.createElement("input");
       inputEl.id = question.id;
       inputEl.type = "text";