[SPARK-1812][wip]

Was just trying out akka 2.3.3 (theoretically it should all work.)
Yeah, you can't write that in the artifact name. It should be a constant string and should stay "2.10". In a PR to upgrade to 2.11 later, all of these should be "2.11" ... which means 2.10 support may have to be a branch at that point? or it may be safe to ignore the warning, if it works.