Juwang-Inserting LoggingScopes

With LoggingScope and LoggingScopeFactory, this PR is to insert LoggingScope in REEF code at major stages to measure the performance. 
This is to resolve issue REEF-28 https://issues.apache.org/jira/i#browse/REEF-28?filter=-1

It was brought back by auto merge as it was still referenced. I just removed it and fixed old reference.