Hi,

I'm using axios v0.17.0 with HEAD method like this:

`axios.head('http://example.com'); `

(let's suppose http://example.com is set to redirect 301 to http://www.example.com)

For some reason Request method will change on the first redirect to GET instead of keeping HEAD all the way down. This will read in logs like this:

```
example.com:80 10.0.0.1 - - "HEAD / HTTP/1.1" 301 237 "-" "axios/0.17.0"
example.com:80 10.0.0.1 - - "GET / HTTP/1.1" 200 246 "-" "axios/0.17.0"
```

instead of this:

```
example.com:80 10.0.0.1 - - "HEAD / HTTP/1.1" 301 237 "-" "axios/0.17.0"
example.com:80 10.0.0.1 - - "HEAD / HTTP/1.1" 200 246 "-" "axios/0.17.0"
```

When I do the test in Firefox it keeps original request method (HEAD) all the way down.

Any idea why is this?

Thanks,
Milos

test/unit/adapters/http.js
}, 100);
    });
  });
  it.skip('should support sockets', function (done) {
    server = net.createServer(function (socket) {
      socket.on('data', function () {
        socket.end('HTTP/1.1 200 OK\r\n\r\n');
      });
    }).listen('./test.sock', function () {
      axios({
        socketPath: './test.sock',
        url: '/'
      })
        .then(function (resp) {
          assert.equal(resp.status, 200);
          assert.equal(resp.statusText, 'OK');
          done();
        })
        .catch(function (error) {
          assert.ifError(error);
          done();
        });
    });
  });
  it('should support streams', function (done) {
    server = http.createServer(function (req, res) {
      req.pipe(res);
    }).listen(4444, function () {
      axios.post('http://localhost:4444/',
        fs.createReadStream(__filename), {