agent/engine/docker_task_engine.go
func (engine *DockerTaskEngine) ListTasks() ([]*apitask.Task, error) {
	return engine.state.AllTasks(), nil
}
func (engine *DockerTaskEngine) ListTasks() ([]*apitask.Task, error) {
	return engine.state.AllTasks(), nil
}
// ListTasks returns the tasks currently managed by the DockerTaskEngine