Authenticate you

        :param username: your username
        :param password: your password

def auth(self, username, password):
        """
        Authenticate you

        :param username: your username
        :param password: your password
        """
        headers = {
            'Content-type': 'application/json'
        }
        payload = {
            'type': self.auth_type,
            'username': username,
            'password': password
        }
        try:
            full_url = utils.urljoin(self.host, '/api/v1/auth')
            response = requests.post(
                full_url,
                data=json.dumps(payload),
                headers=headers,
                verify=self.tls_verify
            )
        except RequestException:
            raise exceptions.TaigaRestException(
                full_url, 400,
                'NETWORK ERROR', 'POST'
            )
        if response.status_code != 200:
            raise exceptions.TaigaRestException(
                full_url,
                response.status_code,
                response.text,
                'POST'
            )
        self.token = response.json()['auth_token']
        self.raw_request = RequestMaker('/api/v1', self.host, self.token,
                                        'Bearer', self.tls_verify)
        self._init_resources()