Better regexp to get country browser from HTTP_ACCEPT_LANGUAGE

With HTTP_ACCEPT_LANGUAGE we have two choices :
* Country == language (displayed with two letter as fr,de,en,...)
* Country with multi language (displayes as fr-CH, de-CH, it-CH)

Previous regexp find only first case.
Merge pull request #488 from camlafit/pr-countriesbrowser

[*] FO : Better regexp to get country browser from HTTP_ACCEPT_LANGUAGE