Fixed groupEdgeTriplets - it now passes a basic unit test.

The problem was with the way the EdgeTripletRDD iterator worked. Calling
toList on it returned the last value repeatedly. Fixed by overriding
toList in the iterator.
Created a MessageToPartition class to send messages without saving the partition id.
Updated Kryo registration.
Merge pull request #17 from amplab/product2

product 2 change
Merge branch 'benchmarks' of github.com:amplab/graphx
Merge pull request #19 from dcrankshaw/master

Merge canonical 2d partitioner and group edges into benchmarks
added support for random vertex cuts
added support for random vertex cuts
added replication and balance reporting
Updated code so benchmarks actually run.
Tried to fix some indenting
Added connected components back
Fixed connected components CL params
Integrated IndexedRDD into graph design.
merging changes from upstream benchmarking branch
merging in master changes
removing benchmark code
trying to address issues with GraphImpl being caught in closures.
Removing extraneous code
Introducing indexedrdd

The rest of indexed rdd