In mapReduceTriplets, walk vertices instead of edges
wip csr dynamic switching
Remove completed TODO
Use float division for activeFraction
Fix activeFraction calculation
Filter deltas using tol to ensure convergence
Merge remote-tracking branch 'origin/csr' into sigmod-pr

Conflicts:
	graph/src/main/scala/org/apache/spark/graph/impl/EdgePartition.scala
	graph/src/main/scala/org/apache/spark/graph/impl/GraphImpl.scala
	graph/src/main/scala/org/apache/spark/graph/impl/VTableReplicated.scala
	graph/src/main/scala/org/apache/spark/graph/impl/VertexPartition.scala
Uncomment edge/vertex walking diagnostics
Sleep if can't save web UI in Analytics
Merge remote-tracking branch 'upstream/sigmod-pr' into sigmod-pr