Add RUnit for DL autoencoder on MNIST.
1) Train autoencoder on 30k rows, unsupervised. Reduce feature space to 20 dimensions.
2) Train supervised model (RF) on the other 30k rows (first transform to 20 dims with AE model).
3) Test this supervised model on 10k test set.
Merge branch 'master' of https://github.com/0xdata/h2o