Code cleanup


SearchOperation.java, SearchOperationBasis.java, SearchOperationWrapper.java:
Changed entriesSent and referencesSent from int to AtomicInteger.
Removed unused fields eclRequestControl, processingStartTime and processingStopTime.
Simplified constructors by initializing the fields during where they are declared.
Extracted method getACIHandler().
Removed incrementEntriesSent() and incrementReferencesSent().
Code cleanup.

Backend.java:
Removed unused code.
Removed ctor, initialized fields where they are declared.

WorkflowTopology.java:
Added toString().
Code cleanup.