Add crossOrigin attribute to imgs to prevent canvas tainted errors

When attempting to load the index.html without using the proxy, I received the following errors -
```
Uncaught SecurityError: Failed to execute 'getImageData' on 'CanvasRenderingContext2D': The canvas has been tainted by cross-origin data. 
```

Adding the ```crossOrigin``` [attribute](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/img#attr-crossorigin) with the value ```annonymous``` fixed the problem.