'Construct a full (\'\'absolute\'\') URL by combining a \'\'base URL\'\' (self)
with a ``relative URL\'\' (relative). Informally, this uses components
of the base URL, in particular the addressing scheme, the network
location and (part of) the path, to provide missing components in the
relative URL.
For more information read RFC 1808 especially section 5.
:param relative: The relative url to add to the base url
:param encoding: The encoding to use for the final url_object being
returned. If no encoding is specified, the returned
url_object will have the same encoding that the current
url_object.
:return: The joined URL.
Example usage available in test_url.py'

def url_join(self, relative, encoding=None):

    resp_encoding = (encoding if (encoding is not None) else self._encoding)
    joined_url = urlparse.urljoin(self.url_string, relative)
    jurl_obj = URL(joined_url, resp_encoding)
    return jurl_obj
