correct typo

I've been spending some time reviewing 6px as a potential service we can rely on for our image manipulation needs. I had some trouble integrating the service in an existing angularjs codebase. Something to do with the usage of Object.keys, I haven't been able to figure it out and I don't want to, that's why i'm searching for a image manipulation api. This pull request fixes a typo in the js client. I have now encountered 2 blocking bugs in your code. The documentation was a bit unclear on what each method actually does when you setup a call. I imagine that someone with less development experience would have been long gone by now. 

The commented out code is breaking in our angularjs app, maybe something to do with: http://stackoverflow.com/questions/25299436/unable-to-call-object-keys-in-angularjs 
```
	Result.Output = function(data) {

		this.data = data;

		this.refs = {};

		//Object.keys(this.data.output).forEach(function(index) {
		//	this.refs[index] = this.data.output[index];
		//}, this);

	};
```