Json options improvements

... options()

Signed-off-by: Julien Viet <julien@julienviet.com>
I realised that while porting the Groovy examples to vertx-groovy:

    def server = vertx.createHttpServer(host: "localhost", port: 4443, ssl: true, keyStoreOptions: [path: 'server-keystore.jks', password: 'wibble'])

versus:

    def server = vertx.createHttpServer(host: "localhost", port: 4443, ssl: true, keyStore: [path: 'server-keystore.jks', password: 'wibble'])

which I think is better. (and yes probably we could change also the underlying Java objects).

Obviously this is purely a cosmetic and subjective concern, so up to you.