The exported request function doesn't have an auth method

Looks like you need to create a Request instance before calling auth.

Without this change, following the readme leads to this:

         TypeError: Object function request(uri, options, callback) {
      if (typeof uri === 'undefined') throw new Error('undefined is not a valid uri or options object.')
      if ((typeof options === 'function') && !callback) callback = options
      if (options && typeof options === 'object') {
        options.uri = uri
      } else if (typeof uri === 'string') {
        options = {uri:uri}
      } else {
        options = uri
      }

      options = copy(options)

      if (callback) options.callback = callback
      var r = new Request(options)
      return r
    } has no method 'auth'