Adding support for alignment tests via sub-datasets

Added sample alignment test for AllGather
Datasets no longer free memory on destruction so Release() must be used

test/test_Reduce.cpp

@@ -40,6 +40,8 @@ namespace CorrectnessTests
             // Check results
             ValidateResults(dataset);
         }
+
+        dataset.Release();
     }
 
     INSTANTIATE_TEST_CASE_P(ReduceCorrectnessSweep,