New way to obtain Accept-language Header

Hi Marc! 

Now, I need languages with country code (es-ES, es-CO, etc). I have seen that server negotiation is not working well at my machine and I was searching solutions. I add a new method to get Accept-language header

I obtain the Accept-language with all browsers, before i didn't

Changes:
Add this method http://php.net/manual/es/locale.acceptfromhttp.php
Delete strtolower line 889 (the good format is es-ES, not es-es)