Replace country with site grain
    
    To allow for multiple sites per country (for example in case of
    locations in multiple cities in one country, or even multiple
    locations in one city), and to make mapping of locations to the
    DCIM/IPAM data (which already uses the site codes) easier, replace
    the "country" grain with a "site" one and refactor logic related to
    it to reflect the change.
    
    References are replaced with the respective, already defined, site
    codes.
    
    Signed-off-by: Georg Pfuetzenreuter <georg.pfuetzenreuter@suse.com>