Enable CORS

[cburgmer]

Adding CORS support (http://www.html5rocks.com/en/tutorials/cors/).

This allows browsers to directly load images from the server via a XMLHttpRequest.

Disabled by default. Can be turned on by setting

server:
  useCors: true

The two headers do the following

• Enable CORS
• Allow the client JS to access the Content-Type header.

[fzaninotto]

Thanks!