Change ctpl implementation to use STL queue & mutex.
Use ctpl synchronized queue instead of boost lockfree queue in bls worker aggregator.
Use smart pointers for memory management of Aggregator and VectorAggregator. With 'delete this;' the objects are prone to data race on the delete operator.
Use smart pointers for memory management of ContributionVerifier.
Pass shared_ptr by value to other threads via worker pool.
