test-driver.js - Adding superclass methods

Adding the start and halt methods for the TestDriver can be used for tests otherwise an exception will be thrown.
Exception: Driver#start method must be overwritten by descendant classes.

lib/test/test-driver.js

@@ -9,5 +9,13 @@ var TestDriver = module.exports = function TestDriver() {
 
 Utils.subclass(TestDriver, Driver);
 
+TestDriver.prototype.start = function(callback) {
+  callback();
+};
+
+TestDriver.prototype.halt = function(callback) {
+  callback();
+};
+
 TestDriver.drivers = ["test"];
 TestDriver.driver = function(opts) { return new TestDriver(opts); };