get the security token by connecting to TouchWorks API

def get_token(self, appname, username, password):
        """
            get the security token by connecting to TouchWorks API
        """
        ext_exception = TouchWorksException(
            TouchWorksErrorMessages.GET_TOKEN_FAILED_ERROR)
        data = {'Username': username,
                'Password': password}
        resp = self._http_request(TouchWorksEndPoints.GET_TOKEN, data)
        try:
            logger.debug('token : %s' % resp)
            if not resp.text:
                raise ext_exception
            try:
                uuid.UUID(resp.text, version=4)
                return SecurityToken(resp.text)
            except ValueError:
                logger.error('response was not valid uuid string. %s' % resp.text)
                raise ext_exception

        except Exception as ex:
            logger.exception(ex)
            raise ext_exception