Moved queue implementation classes to impl package
Moved the executor implementation code to the impl package so it is clear to the end user it is private code and to allign it with modules like mapreduce/replicatedmap
Minor checkstyle supression file improvements
Merge pull request #3097 from pveentjer/cleanup/3.x/executor-package-cleanup

Executor impl code to impl package
Merge pull request #3099 from pveentjer/cleanup/3.x/queue-impl-package

Moved queue implementation classes to impl package
Moved replicated map implementation classes to impl package