Create messenger-tests.ts

* this close to the surface area that we use - i don't feel comfortable adding more info without having actual usage

messenger/messenger-tests.ts

@@ -0,0 +1,14 @@
+/// <reference path="messenger.d.ts"/>
+
+var message = Messenger().post({
+    message: "message",
+    hideAfter: 5,
+    showCloseButton: true,
+    type: "error"
+});
+message.update({
+    type: "error",
+    message: "Error calculating position"
+});
+
+Messenger().hideAll();