Full Cross Origin Resource Sharing for "Counter"

Hi @Globulopolis

This is the patch I sent you yesterday regarding the CORS supper in your plugin.
I integrated my changes directly from the head of your code, so that could be made available as soon as you've reviewed my code.

Please, feel free to contact me if you have any question.

Should you need to see it in action, please look at 
* http://ffnatation.fr
* http://alsace.ffnatation.fr

Cheers