There should be a simple method to get all the tasks

[BackEndCode]

OkDownload Version

v1.0.2-SNAPSHOT

Problem Describe

There should be easy and simple method to get all the running, completed and failed tasks just like the fetch downloader provide. Something like this.

//Query all downloads
fetch.getDownloads(new Func<List<? extends Download>>() {
    @Override
        public void call(List<? extends Download> downloads) {
            //Access all downloads here
        }
});

Log

There is the whole log from LogCat when I occur the problem(I know we can use this tool to let log more readable):