function formatText(req, res, body) {
    // if body is null, default to empty string
    var data = '';

    data = body.toString();

    // TODO: setting the content-length header is not a formatting
    // feature and should be separated into another module
    res.setHeader('Content-Length', Buffer.byteLength(data));
    return data;
}
Formats the body to 'text' by invoking a toString() on the body if it
exists. If it doesn't, then the response is a zero-length string.

@public
@function formatText
@param    {Object} req - the request object (not used)
@param    {Object} res - the response object
@param    {Object} body - response body. If it has a toString() method this
                          will be used to make the string representation
@returns  {String} data