Abitily to use host system language/regional settings

I believe that any serious program must use system-wide settings, like language/regional settings. No such settings is used in XBMC for now. 
That might confuse inexperienced users that are forced to find and change language after first XBMC installation. Problem is even worse if user doesn't know English.
This PR add support for using host system regional settings as default XBMC language/regional settings. User is still free to change XBMC regional settings, default settings are used only at first XBMC run and after XBMC settings reset.
Code is trying to find best matching language and region. If no suitable language is found, code defaulting to "English", If system region is not available in XBMC, than language default region is used.

Code in this PR detects host system setting on Win32 and Linux platforms, but platform support can be easily extended.