Add Comments to MainOrchestrator, MorphemesAnalyzerActor, and MorphemesTrendDetectActor.scala

Squashed commit of the following:

commit 9c6db4696bc6397aaf60c9a097d424d76ba9eb24
Author: Lloyd <lloydmeta@gmail.com>
Date:   Wed Jun 12 19:28:32 2013 +0900

    add comments to 3 actors