Add module declaration for SimpleModal.

jquery.simplemodal/jquery.simplemodal.d.ts

@@ -116,3 +116,8 @@ interface JQueryStatic {
 interface JQuery {
     modal: SimpleModal.JQueryExtension;
 }
+
+/** Ambient wrapper so it can be loaded through require. */
+declare module 'simplemodal' {
+    export = SimpleModal;
+}