Log current Pregel iteration

(cherry picked from commit 54cbd2b4640db13a9cb10ce693e86b776d003907)

Conflicts:
	graphx/src/main/scala/org/apache/spark/graphx/Pregel.scala
In Analytics, take PageRank numIter

(cherry picked from commit bcc79f2cfb7f26da43326d905e2d317f33ff45ee)
In GraphLoader, coalesce to minEdgePartitions

(cherry picked from commit 1993225fde2c8f55b12644e47b7f874b68bd5d69)

Conflicts:
	graphx/src/main/scala/org/apache/spark/graphx/GraphLoader.scala