PUB-837: Add collective (broadcast+reduce) network test using MRTask2.
PUB-989: Add auto-tuning of train_samples_per_iteration, and make that default.
PUB-989: Add JUnit tests for auto-tuning.
PUB-989: Add R documentation for auto-tuning.
PUB-989: Add auto-tuning to the R Vignette for DL.
Merge branch 'arno-deeplearning2'