higher-level content negotiation for Node.js

 Higher level content negotiation based on negotiator.
 .
 In addition to negotiator, it allows:
  - Allows types as an array or arguments list, ie
    `(['text/html', 'application/json'])`
    as well as `('text/html', 'application/json')`.
  - Allows type shorthands such as `json`.
  - Returns `false` when no types match
  - Treats non-existent headers as `*`
 .
 Node.js is an event-based server-side JavaScript engine.