Merge pull request #60 from amplab/rxin

Looks good to me.
Optimize mrTriplets for source-attr-only mapF using bytecode inspection
Test no vertex attribute replication
Create all versions of vid2pid ahead of time
Factor out VTableReplicatedValues
Add test for mapReduceTriplets in GraphSuite
Fix typo
Use pid2vid for creating VTableReplicatedValues
Build pid2vid structures only once, in Vid2Pid
Handle ClassNotFoundException from ByteCodeUtils

ByteCodeUtils.invokedMethod(), which we use in mapReduceTriplets, throws
a ClassNotFoundException when called with a closure defined in the
console. This commit catches the exception and conservatively assumes
the closure references all edge attributes.
Merge pull request #55 from ankurdave/aggregateNeighbors-variants

Specialize mapReduceTriplets for accessing subsets of vertex attributes
Merge pull request #61 from ankurdave/pid2vid

Shuffle replicated vertex attributes efficiently in columnar format
Cleanning up documentation of VertexSetRDD.scala
Removing extra unused code.
Merge pull request #64 from jegonzal/VertexSetCleanup

Commenting out additional not strictly necessary code.