Improve UrlMappings to allow support for collections and members

[graemerocher]

When mapping resources UrlMappings should allow nested resources directly within the parent URI. These URL mappings should match:

       "/books"(resources: "book") {
            get "/preview", action:"preview"
            collection {
                get "/about", action:"about"
            }
        }

As follows

    urlMappingsHolder.matchAll("/books/1/preview", HttpMethod.GET)
    urlMappingsHolder.matchAll("/books/about", HttpMethod.GET)