[Router] Implement type-safe router

[danneu]

The API could look something like this:

Router {
    get("/users/:id", fun(id: Int): Handler = { req ->
        Response().text("User $id")
    })
}

TODO:

• [x] Middleware tests
• [x] Figure out a good group("/prefix") API.
• [x] Support websockets
  • Could map SafeRouter patterns into jetty context paths with wildcards: http://stackoverflow.com/questions/4798120/is-it-possible-to-use-regular-expression-for-jettys-servlet-mapping
• [x] Build router using reflection once so that the router isn't using reflection (slow) during dispatch. Right now it naively uses reflection on every request when instead it should compile a mapping at init. (Even though I improved it and checked the box, more work could be done)
• [x] Consider compiling one regex that maps requests to handlers.

[danneu]

Got the gist of it working: https://github.com/danneu/kog/commit/143f929e22cd1c998bb375ba530f2de476c5fdfd

Though isn't yet feature-full.

[danneu]

Deleted the old Router.kt and renamed SafeRouter.kt to Router.kt.