yaml

This changes the format of the required configuration file to yaml, to stay in line with the other conf files. The data inside is the same, but in yaml.
Sounds good, I have no problem with this @Galithil 
@pekrau - can we just rename the key to `domain` instead of doing parsing? The key nomenclature is arbitrary in this code I think. It's constructed into an address to connect to below:

```python
self.url_string = "http://{}:{}@{}:{}".format(self.user, self.pw, self.url, self.port)
```