In my case I have a `http_proxy` env variable on my development computer which passes all traffic to my vpn, however this proxy would fail to work when hostname is `localhost`, therefore when I'm testing my application it always fails because I setup my server at localhost, I want a method to force axios receiving a `none` for proxy config, currently if `proxy` property is `null` or `undefined` it will use the `http_proxy` env
test/unit/adapters/http.js
response.end(body + '6789');
          });
        });
      }).listen(4000, function() {
        axios.get('http://localhost:4444/', {
          proxy: {
            host: 'localhost',
            port: 4000
          }
        }).then(function(res) {
          test.equal(res.data, '123456789', 'should pass through proxy');
          test.done();
        });
      });
    });
  },
  testHTTPProxyEnv: function(test) {
    server = http.createServer(function(req, res) {
      res.setHeader('Content-Type', 'text/html; charset=UTF-8');
      res.end('4567');
    }).listen(4444, function() {
      proxy = http.createServer(function(request, response) {
        var parsed = url.parse(request.url);
        var opts = {
          host: parsed.hostname,
          port: parsed.port,
          path: parsed.path
        };
        http.get(opts, function(res) {
          var body = '';