Allow path params to use "normal" `{ }` as well as `:` for Javalin

[rbygrave]

So for Javalin we can do:

@Get("{id}/{type}")                      // <!-- more standard style using {}
List<Foo> getFoos(long id, String type) ...


@Get(":id/:type")                         // <!-- Javalin colon style
List<Foo> getFoos(long id, String type) ...