Added CORS headers and listening support for all interfaces

* Added autodetection support for CORS headers if 'Origin' header is present in the request, according with the [W3C specification](http://www.w3.org/TR/cors/#origin-request-header)

* I've had a minor trouble with the `location` config option. In the documentation it refers to the listening hostname, but in a server context is more usual to think about interfaces (IP addresses instead of resolution hostnames). 
In some scenarios you want to listen in all interfaces, for example if you are working inside a virtual dev environment and want to forward some ports to the guest.
In order to give a neutral solution, I added support to use the wildcard character, that is just an alias equivalent to the non-enturable IP address (`INADDR_ANY`). Only IPv4, maybe also add support to IPv6?

Test specs also was added, but maybe worth to review or improve by the way...

Thanks!

PS: forget about the latest both PR, it was a mistake! I'm sorry!