'Import field data content for field other than \'data\' or \'metadata\' form json file and
return field data content as dictionary'

def _import_field_content(self, course_descriptor, category, file_path):

    (slug, location, data_content) = (None, None, None)
    try:
        (dirname, field, file_suffix) = file_path.split('/')[(-1)].split('.')
        if ((file_suffix == 'json') and (field not in DEFAULT_CONTENT_FIELDS)):
            slug = os.path.splitext(os.path.basename(dirname))[0]
            location = course_descriptor.scope_ids.usage_id.replace(category=category, name=slug)
            with open(file_path) as field_content_file:
                field_data = json.load(field_content_file)
                data_content = {field: field_data}
    except (IOError, ValueError):
        data_content = None
    return (slug, location, data_content)
