"Hang Closing" option doesn't work.

I can't seem to get closing brackets to outdent automatically using this package.

```python
a = {
1: 2,
3: 4,
}
```

When I type that, and press Enter after the fourth line, the leading whitespace should be removed when I have the "Hang Closing" option checked, but it doesn't.

Atom version: 1:27.2
ide-python version: 1.0.0

Reproduce the example in Atom with ide-python 1.0.0 and the "Hang Closing" option enabled. Trace how Enter handles the closing bracket indentation, then verify that the leading whitespace is removed for the shown Python dictionary while other indentation behavior remains unchanged.

Written by the indexing model from the issue text.