Case indentation error

Hello,

First thank you for your work. I have a problem with haskell-indentation-mode: when I do

```
"fact n =<RET>case n of<RET>1 -> 0<RET>n -> n * fact (n-1)"
```

I have

```
fact n =
  case n of
  0 -> 1
  _ -> n * fact (n - 1)
```

while I would like to have

```
fact n =
  case n of
    0 -> 1
    _ -> n * fact (n - 1)
```

Do you have any solution ?

Thank you for you work !
