GIRAPH-501: WorkerObserver (nitay)
GIRAPH-501: WorkerObserver (nitay)

dukechain/giraph-1.2,apache/giraph,korsvanloon/giraph,korsvanloon/giraph,mmaro/giraph,Cdbot100/giraph,basio/graph,pgrm/giraph,dcrankshaw/giraph,dukechain/giraph-1.2,dukechain/giraph-1.2,dukechain/giraph-1.2,basio/graph,korsvanloon/giraph,apache/giraph,pmPartch/giraph,dcrankshaw/giraph,basio/graph,korsvanloon/giraph,Cdbot100/giraph,apache/giraph,pmPartch/giraph,pgrm/giraph,KidEinstein/giraph,basio/graph,KidEinstein/giraph,KidEinstein/giraph,KidEinstein/giraph,mmaro/giraph,apache/giraph,skymanaditya1/giraph,dukechain/giraph-1.2,apache/giraph,dukechain/giraph-1.2,apache/giraph,skymanaditya1/giraph,mmaro/giraph,dcrankshaw/giraph,mmaro/giraph,korsvanloon/giraph,korsvanloon/giraph,dcrankshaw/giraph,KidEinstein/giraph,KidEinstein/giraph