Merge pull request #492 from telefonicaid/hardening/harness_errors_under_valgrind

Hardening/harness errors under valgrind
REFACTOR using DBClientBase intead of DBClientConnection, preparing for the replSet driver connection
ADD -rplSet paramter to command line
ADD replicaset connections implementation
ADD BROKER_DATABASE_RPLSET variable
ADD entry to CHANGES_NEXT_RELEASE
added -rplSet parameter if mongo in replicaset is configured
ConetextBroker start parameters refactored
Update CHANGES_NEXT_RELEASE
FIX leftover comment
FIX issues rasied in code review
Merge pull request #497 from telefonicaid/bug/493

ReplicaSet support (into develop)