Support ipv6 in geoinfo and Embargo

When someone access the OpenedX website with ipv6 address,GeoIPError('Invalid database type; expected IPv4 address') raised , because we didnot provide GeoIPv6.dat when try to exec  
  country_code = pygeoip.GeoIP(DB_PATH).country_code_by_addr(new_ip_address)
Embargo is also the case


@sarina @singingwolfboy