Currently, if you use axios with async / await, you get a stack trace like this:

```
Request failed with status code 500
    at createError (/Users/rmenezes/code/seedfi/web/node_modules/axios/lib/core/createError.js:16:15)
    at settle (/Users/rmenezes/code/seedfi/web/node_modules/axios/lib/core/settle.js:17:12)
    at IncomingMessage.handleStreamEnd (/Users/rmenezes/code/seedfi/web/node_modules/axios/lib/adapters/http.js:237:11)
    at IncomingMessage.emit (events.js:208:15)
    at IncomingMessage.EventEmitter.emit (domain.js:471:20)
    at endReadableNT (_stream_readable.js:1154:12)
    at processTicksAndRejections (internal/process/task_queues.js:77:11
```

It doesn't show you much about *what* called Axios., which makes debugging quite difficult!

This is because `settle` calls `createError`:
https://github.com/axios/axios/blob/master/lib/core/settle.js#L12-L24

Which creates a new error with a brand new stack trace:
https://github.com/axios/axios/blob/master/lib/core/createError.js#L15-L18

Perhaps we can fix this by creating an error before the request goes out and stitching it to the new error's stack trace?
test/unit/adapters/http.js
}).listen(4444, function () {
      axios.get('http://localhost:4444/', {
        params: {
          errorParam: new Date(undefined),
        },
      }).catch(function (err) {
        assert.deepEqual(err.exists, true)
        done();
      }).catch(done);
    });
  });
  it('should support sockets', function (done) {
    // D
    var socketName = './test.sock';
    if (process.platform === 'win32') {
      socketName = '\\\\.\\pipe\\libuv-test';
    }
    server = net.createServer(function (socket) {
      socket.on('data', function () {
        socket.end('HTTP/1.1 200 OK\r\n\r\n');
      });
    }).listen(socketName, function () {
      axios({
        socketPath: socketName,
        url: 'http://localhost:4444/socket'
      })
        .then(function (resp) {
          assert.equal(resp.status, 200);
          assert.equal(resp.statusText, 'OK');
          done();