Volume yaml 271

fixes #271 
If we go with ascii only then this encoding is unnecessary because yaml will produce `bytes` for ascii-only strings.

```
>>> type(safe_load(u'"\N{SNOWMAN}"'.encode('utf-8')))
<type 'unicode'>
>>> type(safe_load(u'"foo"'.encode('utf-8')))
<type 'str'>
>>> 
```

It's utterly awful but oh well.