title: Cannot import declaration file
body: <p>I'm trying to set up some test for my RESTAPI server. I use typescript.
  I tried to import <code>chai</code> and <code>chai-http</code> using the ES6 syntax, but apparently, it's not supported (<a href="https://github.com/DefinitelyTyped/DefinitelyTyped/issues/19480" rel="nofollow noreferrer" title="Github issue">Github issue here </a>). I get an error, so I had to <code>require</code> the files directly.</p>
  
  <pre><code>var chai = require('chai')
      , chaiHttp = require('chai-http');
  
  import *  from '@types/chai-http';
  
  /* 
   * Both librairies have limited support of ES6 import.
   * See https://github.com/DefinitelyTyped/DefinitelyTyped/issues/19480
  */
  
  chai.use(chaiHttp);
  
  import { expect } from 'chai' ;
  import 'mocha';
  </code></pre>
  
  <p>Now the thing is typescript doesn't import <code>@types/chai-http</code> for some reason, so when I try to use <code>expect(res).to.have.status(201);</code>, I get an error, the compiler complain </p>
  
  <pre><code>Error TS2339: Property status does not exist on type Assertion
  </code></pre>
  
  <p>How do I import the type declaration directly?</p>
  
  <p>Thanks</p>