TLOG — support QoS properties

I'm working on TAO's Log Service implementation, and I'm not sure how I'm supposed to support QoS properties. The spec for get_log_qos() method states it "returns a list of the quality of service properties supported by the log." This is different from the other get_* methods, which return the current value of the settings. If this is the intent, it should be emphasized, and perhaps a new method introduced to fetch the current QoS settings. The three defined QoS settings QoSNone, QoSFlush, and QoSReliability are mutually exclusive. But unlike the Notification Service Spec's section on QoS settings, there is no guideance wrt. semantics of a property list with multiple properties or what should be returned in the denied list in the UnsupportedQoS exception.