Fixed issue with firefox cached body causing s3.headObject to error

If Firefox does a s3.headObject on a cached object, it will return the body of that file. The aws-sdk-2.0.0-rc11 uses the wrong assumption that its an S3 XML response and will parse it as XML. 

Example:
If the file has non xml such as a jpg file, aws-sdk-2.0.0-rc11 will throw errors trying to read it.

Test code:

It his test code Body: 'hello' is not valid XML from S3
````````````````````````
<!DOCTYPE html>
<html>
  <head>
    <script type="text/javascript" src="https://sdk.amazonaws.com/js/aws-sdk-2.0.0-rc11.js"></script>

  </head>
  <body>
    <div id="status"></div>
    <script type="text/javascript">
	AWS.config = {
		accessKeyId: '......',
		secretAccessKey: '......'
	};
	s3 = new AWS.S3({params: {Bucket: '........', Key: 'key.txt'}});


	var elem = document.getElementById('status');

      elem.innerHTML="userAgent: " + navigator.userAgent + "<hr/>";
      s3.putObject({Body: 'hello', ContentType: 'text/html'}, function (err, data) {
        elem.innerHTML+="Write example data - putObject.ETag: " + (err ? err.stack : data.ETag) + "<hr/>";

	s3.headObject({}, function (err, data) {
        	elem.innerHTML+="Test if it works not cached - headObject.ETag: " + (err ? err.stack : data.ETag) + "<hr/>";

		s3.getObject({}, function (err, data) {
			elem.innerHTML+="So we have it cached - getObject.ETag: " + (err ? err.stack : data.ETag) + "<hr/>";

			s3.headObject({}, function (err, data) {
				elem.innerHTML+="Test if it works cached - headObject.ETag: " + (err ? err.stack : data.ETag) + "<hr/>";
		      	});

	      	});
      	});

      });
    </script>
  </body>
</html>
````````````````````````

Firefox before Fix:
````````````````````````````````````
userAgent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:27.0) Gecko/20100101 Firefox/27.0

Write example data - putObject.ETag: "5d41402abc4b2a76b9719d911017c592"

Test if it works not cached - headObject.ETag: "5d41402abc4b2a76b9719d911017c592"

So we have it cached - getObject.ETag: "5d41402abc4b2a76b9719d911017c592"

Test if it works cached - headObject.ETag: error@https://sdk.amazonaws.com/js/aws-sdk-2.0.0-rc11.js:11974 strictFail@https://sdk.amazonaws.com/js/aws-sdk-2.0.0-rc11.js:11994 write@https://sdk.amazonaws.com/js/aws-sdk-2.0.0-rc11.js:12244 [73]
````````````````````````````````````

Firefox after Fix:
````````````````````````````````````
userAgent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:27.0) Gecko/20100101 Firefox/27.0

Write example data - putObject.ETag: "5d41402abc4b2a76b9719d911017c592"

Test if it works not cached - headObject.ETag: "5d41402abc4b2a76b9719d911017c592"

So we have it cached - getObject.ETag: "5d41402abc4b2a76b9719d911017c592"

Test if it works cached - headObject.ETag: "5d41402abc4b2a76b9719d911017c592"
````````````````````````````````````

I added "Body": {"type": "binary","streaming": true }, and  "payload": "Body" to fix the issue. 

Concerns:

1) I'm not sure why the all of the files say they where updated 3 days ago. Are these files from a conversion?
2) Body will only be returned by browsers such as Firefox.