from_string Miss-Parses Spaces

```
$ perl -MData::UUID -E 'my $u = Data::UUID->new; my $uuid = $u->from_string("91ae3596 95fa 11e4 ab6c 6cff01d6b4db"); say $u->to_string($uuid)'
91AE3596-955F-0A11-E4AB-B60C6CFF01D6
```

That output should be

```
91AE3596-95FA-11E4-AB6C-6CFF01D6B4DB
```

It seems to think the spaces are significant. :-(
