Updated the compute reference solution function to accept the aggregation operation as a template argument. Implemented computing the AVG reference solution.
Updated the compute reference solution function to accept the aggregation operation as a template argument. Implemented computing the AVG reference solution.

gpuopenanalytics/libgdf,gpuopenanalytics/libgdf,gpuopenanalytics/libgdf,gpuopenanalytics/libgdf