Function eventual::background

pub fn background<R: Run<Box<TaskBox>> + Send + 'static, F: FnOnce() -> T + Send + 'static, T: Send>(
    task_runner: R, 
    closure: Box<F>
) -> Future<T, ()>

This method backgrounds a task onto a task runner waiting for complete to be called. Currently we only support using a ThreadPool as the task runner itself.