Config changes

[belak]

I realize that this isn't required, but I thought of the possibility of switching the config to a json format. This way, we can avoid one more non-std lib import.

It's really simple to open a new file, and throw the io.Reader into a json.Decoder. Then you just unmarshal into the struct representing the whole config file. Note that I don't have a pull request for this since it's more of an idea than anything else right now, but if you're interested, I may be willing to throw one together.

[fizx]

I don't really like json as a config file format. It doesn't allow comments, which is really annoying because I think that the configs benefit from the inline documentation. I do like the idea of unmarshalling through the json pipeline. In Java, Jackson has great unmarshalling, but SnakeYaml doesn't, so Dropwizard just changes YAML to a Map<String, Object> and passes it though the json unmarshaller. Maybe something similar could happen.