GAE: create a typesafe Task Queue scheduler

[sergiolopes]

Lucas wrote an initial version for an internal Caelum project (caelumsite). We may want to include this in the VRaptor's GAE plugin.

[lucascs]

Ideas for the API:

interface TaskScheduler {
     TaskScheduler with(String queueName);
     <T> T start(Class<T> type); // sched.start(Controller.class).method();
     <T> T start(T controller); // sched.start(this).method();
}

only URI's starting with "/tasks"?
creating an @task ?
Something about retries?
Something about future tasks?