(TK-20) Webrouting Service

This PR adds a new optional webrouting service that can replace a project's dependency on the Jetty9 webservice. It offers the same functionality as the webservice, but allows the user to specify the endpoints they want specific services to register in their configuration file and add them by passing in the namespaced symbol of a service rather than directly passing in an endpoint.
Actually, now that I think about it--I think I was imagining that your callers wouldn't need to call either `service-symbol` or `keyword`, I was thinking they'd just pass in the service object directly?  In an ideal world they could just pass in `this`, but I'm guessing maybe that doesn't work as of today due to the implementation of the `defservice` macro?  But passing in the result of the call to `get-service` should work, right?