Blubber does not currently validate user-provided configuration beyond what go-yaml inherently provides, hence errors related to bad config are very obscure. Let's see about implementing:

1. Wrapping of YAML parsing errors (type errors, mostly) to be more user friendly
2. Definition/implementation of a validation interface for config parts
3. Errors upon missing config elements required by other config, etc.
4. Errors upon unknown YAML config elements (they are currently just ignored by the YAML parser)