Add RDD.tupleBy.
Rename RDD.tupleBy to keyBy.
Log preferred hosts
Fixing if/else coding style for preferred hosts logging
Merge branch 'master' into tupleBy

Conflicts:
	core/src/test/scala/spark/RDDSuite.scala
Add JavaRDDLike.keyBy.
Merge pull request #353 from stephenh/tupleBy

Add RDD.tupleBy.
Merge pull request #344 from mbautin/log_preferred_hosts

Log preferred hosts