Allow null/empty response body

[opsonusi]

For example:

post("/accounts", { req, res -> res.status(201) })

Currently this fails with as a 404.
INFO spark.webserver.MatcherFilter - The requested route [/accounts] has not been mapped in Spark

In MatcherFilter.java:227, bodyContent == null is not enough to indicate the request hasn't been consumed.

        boolean consumed = bodyContent != null;

        if (!consumed && hasOtherHandlers) {
            throw new NotConsumedException();
        }

        if (!consumed && !isServletContext) {
            LOG.info("The requested route [" + uri + "] has not been mapped in Spark");
            httpResponse.setStatus(HttpServletResponse.SC_NOT_FOUND);
            bodyContent = String.format(NOT_FOUND);
            consumed = true;
        }

[Tradunsky]

The pull request:
#352
should fix the issue

[tipsy]

I've changed my mind here, this actually makes sense. If the route is null, nothing has been mapped, so 404 is appropriate.