Reuse VTableReplicated in GraphImpl.subgraph
Remove unused EdgePartition.filter
Merge pull request #120 from ankurdave/subgraph-reuses-view

Reuse VTableReplicated in GraphImpl.subgraph
Fixing the persist behavior of the Vertex and Edge RDDs to persist the current RDD and not the parent.
Addressing issue in compute where compute is invoked instead of iterator on the parent RDD.
Merge pull request #126 from jegonzal/FixingPersist

Fixing Persist Behavior