Load the resource listing from file, handling errors.

    :param resource_listing: path to the api-docs resource listing file
    :type  resource_listing: string
    :returns: contents of the resource listing file
    :rtype: dict

def _load_resource_listing(resource_listing):
    """Load the resource listing from file, handling errors.

    :param resource_listing: path to the api-docs resource listing file
    :type  resource_listing: string
    :returns: contents of the resource listing file
    :rtype: dict
    """
    try:
        with open(resource_listing) as resource_listing_file:
            return simplejson.load(resource_listing_file)
    # If not found, raise a more user-friendly error.
    except IOError:
        raise ResourceListingNotFoundError(
            'No resource listing found at {0}. Note that your json file '
            'must be named {1}'.format(resource_listing, API_DOCS_FILENAME)
        )