attach the dropdown to the element's body instead of the current body. issue select2#126

Author: ivaynberg

select2.js

@@ -668,7 +668,7 @@
             if (this.opened()) return;
 
             this.container.addClass("select2-dropdown-open").addClass("select2-container-active");
-            this.dropdown.detach().appendTo('body').addClass("select2-drop-active");
+            this.dropdown.detach().appendTo(this.opts.element.parents("body")).addClass("select2-drop-active");
 
             this.positionDropdown();