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.
I think it would be most useful for the users of this code if it falls over if no config file is present to be honest. I can't think of many (any) circumstances where people would want to run it without one?

And yeah, probably worth checking for the attributes and bailing before trying to log in with a malformed URL.. Should give a more informative error.