Unpacks a post request query string.
    :param environ: whiskey application environment.
    :return: A dictionary with parameters.

def unpack_post(environ, content_length):
    """
    Unpacks a post request query string.
    :param environ: whiskey application environment.
    :return: A dictionary with parameters.
    """
    post_body = environ['wsgi.input'].read(content_length).decode("utf-8")
    data = None
    if "application/x-www-form-urlencoded" in environ["CONTENT_TYPE"]:
        data = dict(parse_qsl(post_body))
    elif "application/json" in environ["CONTENT_TYPE"]:
        data = json.loads(post_body)

    logger.debug("unpack_post:: %s", data)
    return data