(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.
It seems like the schemas in `puppetlabs.trapperkeeper.services.webserver.jetty9-core` could be-used here (with the addition of the optional `:route-id`) to avoid the duplication.