Option Request: space-between-nested-blocks

I would like to suggest an option, space-between-nested-blocks.  For my needs, I'd just like to make sure there is a line between my current rules and a nested selector.  Example:
### Example Source

```
.foo {
  color: black;
  .bar {
    color: gray;
  }
}
```
### space-between-nested-blocks = true

```
.foo {
  color: black;

  .bar {
    color: gray;
  }
}
```
