Make the dhashclient extendable by making gwclnt protected, and adding a protected null constructor.
Make the dhashclient extendable by making gwclnt protected, and adding a
protected null constructor.

sit/dht,weidezhang/dht,sit/dht,sit/dht,weidezhang/dht,sit/dht,weidezhang/dht,weidezhang/dht,sit/dht,weidezhang/dht