Only ignore Status changed note emails if system, not if made by users.


Currently, if you make an issue comment that starts with the magic string:

    _Status changed to closed_

no notifications are generated.

After this PR they are, using the same mechanism that fixed this problem for `_mentioned in` notes, by first doing a `note.system` check.
I have no strong feeling about this, but I think that aligning is more analogous to bbatsov's method and array align at params rule. Just imagine we had a (God forbid) 2 char method call:

```
f2 a,
    b
```

would be analogous to if in that case.