shed_init produces yaml with Pythonic types described

`planemo shed_init --name=seqtk_test --owner=planemo --description="seqtk wrapper for test"`

produces

```
description: !!python/unicode 'seqtk wrapper for test'
name: !!python/unicode 'seqtk_test'
owner: !!python/unicode 'planemo'
```

it still works with other Planemo commands but maybe is not valid .yaml and the types are not neccesary I think.
