Feature/json resource

Make it possible to fo a GET that returns handler info as JSON. It is conceptually similar to the debug request in that it does not make a subsequent upstream call. The motivation is that an application can make a call to the deviceproxy service outside the request-response loop.
I'm trying to fit a square peg in a round hole here. I don't really want headers back at all - I just want a JSON result from a handler. But deviceproxy was written to be a proxy and thus passes info along in headers. If I enforce that handlers must return unicode strings then my JSON handler will have some ugly code in there. Options:
1. Set headers as usual. Client can pull what it wants from it. Return 'OK' response.
2. Special handling for a certain header in the JSON handler. I don't like this.

I'll adjust code to show you what (1) will look like.