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)?

lib/adapters/xhr.js
request = null;
  };
  
  
  
  if (utils.isStandardBrowserEnv()) {
    var cookies = require('./../helpers/cookies');
    
    var xsrfValue = config.withCredentials || isURLSameOrigin(config.url) ?
        cookies.read(config.xsrfCookieName) :
        undefined;
    if (xsrfValue) {
      requestHeaders[config.xsrfHeaderName] = xsrfValue;
    }
  }
  
  if ('setRequestHeader' in request) {
    utils.forEach(requestHeaders, function setRequestHeader(val, key) {
      if (typeof requestData === 'undefined' && key.toLowerCase() === 'content-type') {
        
        delete requestHeaders[key];
      } else {
        
        request.setRequestHeader(key, val);
      }
    });
  }
  
  if (config.withCredentials) {
    request.withCredentials = true;