Adding the ability to set and get locale

This pull will add the ability to set and get locale to system settings.  
Please use const var instead of define.
```
namespace {

const char sDBusProp[] = "org.freedesktop.DBus.Properties";
const char sInterfaceName[] = "org.freedesktop.locale1";
const char sObjectPath[] = "/org/freedesktop/locale1";

}  // namespace anonymous 
```