Remove spr knowledge dependency

[LarsJanssenTUe]

In answer_question.py:

        #To do: remove this dependency!
        self._speech_data = load_knowledge('challenge_spr')
        if not self._speech_data:
            rospy.logerr("Failed to load speech data for 'AnswerQuestion' action")
            return

[LarsJanssenTUe]

After discussion with @MatthijsBurgh it is decided that this specific knowledge should be transferred to the common knowledge, but we do not know what to do with the issue itself that knowledge is being loaded here without checking