Support ASK SDK v2 for Node.js

[gavinr]

As of April 2018, there is a new ASK SDK for Node.js (link, link). The format for responding to intent requests is now:

return handlerInput.responseBuilder

    .speak(speechOutput)

    .withSimpleCard(SKILL_NAME, randomFact)

    .getResponse();

How is the best way to use this library with this new format?