inamiy/SwiftTask — pull request #1 by inamiy (2014-08-25 23:38:14+00:00)
Title: Improve future binding.

There was a bug when:

```
let task3 = task1.then { return task2}

...

// cancel when task1=fulfilled, task2=running
task3.cancel()
XCTAssertEqual(task2.state, .Cancelled) // FAIL
```

so I fixed this by configuring `task3` to associate with future `task2`'s pause/resume/cancel.