Use the DelegateAuthRequest to provide a token and his lifetime
        for the provided account.

        If account is provided we use it,
        else we retreive the account from the provided account_name.

def get_account_authToken(self, account=None, account_name=''):
        """ Use the DelegateAuthRequest to provide a token and his lifetime
        for the provided account.

        If account is provided we use it,
        else we retreive the account from the provided account_name.
        """
        if account is None:
            account = self.get_account(zobjects.Account(name=account_name))
        selector = account.to_selector()

        resp = self.request('DelegateAuth', {'account': selector})

        authToken = resp['authToken']
        lifetime = int(resp['lifetime'])

        return authToken, lifetime