Per node stonith config

Fixes https://bugzilla.novell.com/show_bug.cgi?id=887244
it is explained in the commit message

```
Pacemaker::Resource.extract_hash() is written to extract things from a complete
CIB object definition. Therefore it rightfully expects whitespaces before the
data_type ("params" in this case). So we just add those here to make the string
parsable by extract_hash.
```