auth - agent update

import superagentPromise from 'superagent-promise';
import _superagent from 'superagent';

// http client
const superagent = superagentPromise(_superagent, global.Promise);

// root api url
const API_ROOT = 'https://conduit.productionready.io/api';

// callback to extract the body out of a response
const responseBody = (res) => res.body;

// variable storing the auth token
let token = null;
// attach authorization token to the request so we can make requests which require
// authorization.
const tokenPlugin = (req) => {
  if (token) {
    req.set('authorization', `Token ${token}`);
  }
};

// http method wrapppers
// make a request to the given url, attach auth header, parse out body
const requests = {
  get: (url) =>
    superagent.get(`${API_ROOT}${url}`).use(tokenPlugin).then(responseBody),
  post: (url, body) =>
    superagent.post(`${API_ROOT}${url}`).use(tokenPlugin).then(responseBody),
};

// articles methods
const Articles = {
  // get promise for 10 articles
  all: (page) => requests.get('/articles?limit=10'),
};

const Auth = {
  // get current user's user object
  current: () => requests.get('/user'),
  // get promise for login success/failure
  login: (email, password) =>
    requests.post('/users/login', {user: {email, password}}),
};

export default {
  Articles,
  Auth,
  // set the token to the passed in parameter
  setToken: (_token) => {
    token = _token;
  },
};