Fix MSE reporting

Was reporting MSE over all rows, but for DRF report MSE divided by all
rows actually tested on some tree.
Add code (disabled) to properly split catagoricals.
Clean up progress-page for DRF & GBM more
Merge branch 'master' of github.com:0xdata/h2o
Missed 2 calls
Merge branch 'master' of github.com:0xdata/h2o