Filer config to set custom private media path
        http://django-filer.readthedocs.org/en/0.9.4/settings.html#filer-storages

def FILER_STORAGES(self):
        """Filer config to set custom private media path
        http://django-filer.readthedocs.org/en/0.9.4/settings.html#filer-storages
        """
        if not self.FILER_CUSTOM_NGINX_SERVER:
            return {}

        return {
            'public': {
                'main': {
                    'ENGINE': self.default_file_storage,
                    'OPTIONS': {},
                    'UPLOAD_TO': 'filer.utils.generate_filename.by_date',
                    'UPLOAD_TO_PREFIX': 'filer_public',
                },
                'thumbnails': {
                    'ENGINE': self.default_file_storage,
                    'OPTIONS': {},
                    'THUMBNAIL_OPTIONS': {
                        'base_dir': 'filer_public_thumbnails',
                    },
                },
            },
            'private': {
                'main': {
                    'ENGINE': 'filer.storage.PrivateFileSystemStorage',
                    'OPTIONS': {
                        'location': self.filer_private_files_path,
                        'base_url': '/smedia/filer_private/',
                    },
                    'UPLOAD_TO': 'filer.utils.generate_filename.by_date',
                    'UPLOAD_TO_PREFIX': '',
                },
                'thumbnails': {
                    'ENGINE': 'filer.storage.PrivateFileSystemStorage',
                    'OPTIONS': {
                        'location': self.filer_private_thumbnails_path,
                        'base_url': '/smedia/filer_private_thumbnails/',
                    },
                    'THUMBNAIL_OPTIONS': {},
                },
            },
        }