IE 11 is giving me a hard time...

I'm trying to send some binary data as a `Uint8Array` in a POST request, but `[Object object]` gets sent instead. In IE's dev tools, inspecting the request body reveals that the `Uint8Array` is being transformed incorrectly as `[Object object]`:

![screen shot 2016-03-15 at 9 31 20 am](https://cloud.githubusercontent.com/assets/440299/13793569/b991e3ea-eab4-11e5-9901-f9adee6f1beb.png)

I tried commenting out some code to see if the request will send the correct data, and it does. I commented out these lines:

```
if (utils.isArrayBuffer(requestData)) {
  requestData = new DataView(requestData);
}
```

https://github.com/mzabriskie/axios/blob/master/lib/adapters/xhr.js#L162

... and the resulting request sent binary data as expected:

<img width="463" alt="screen shot 2016-03-15 at 7 14 07 pm" src="https://cloud.githubusercontent.com/assets/440299/13800038/27c28680-eae2-11e5-9718-512fcc078cd7.png">

What is the purpose of the `new DataView()` call? What is happening that turns the binary data into the `[Object object]` string? Why does this break only in IE 11 (works in Chrome, Firefox, Edge)?

test/specs/requests.spec.js
done();
    });
  });
  it('should reject on network errors', function (done) {
    
    jasmine.Ajax.uninstall();
    var resolveSpy = jasmine.createSpy('resolve');
    var rejectSpy = jasmine.createSpy('reject');
    var finish = function () {
      expect(resolveSpy).not.toHaveBeenCalled();
      expect(rejectSpy).toHaveBeenCalled();
      done();
    };
    axios('http://thisisnotaserver')
      .then(resolveSpy, rejectSpy)
      .then(finish, finish);
  });
  it('should reject when validateStatus returns false', function (done) {
    var resolveSpy = jasmine.createSpy('resolve');
    var rejectSpy = jasmine.createSpy('reject');
    axios('/foo', {
      validateStatus: function (status) {
        return status !== 500;
      }
    }).then(resolveSpy)
      .catch(rejectSpy)
      .then(function () {
        expect(resolveSpy).not.toHaveBeenCalled();
        expect(rejectSpy).toHaveBeenCalled();
        done();