Improve node registry test coverage

test/red/runtime/nodes/resources/local/TestNode2/TestNode2.js

@@ -0,0 +1,10 @@
+// A test node that exports a function which returns a resolving promise
+
+var when = require("when");
+module.exports = function(RED) {
+    return when.promise(function(resolve,reject) {
+        function TestNode(n) {}
+        RED.nodes.registerType("test-node-2",TestNode);
+        resolve();
+    });
+}