Slower GBM test-on-train test

Need to perf test, so need a slower model-build
Has ugly cut-n-paste CM printing.
GBM 10% hack

Preload the smallish residual vector before doing the for-all-cols loop.
Basically moves a (very short) for-all-classes loop out of a
for-all-cols loop.
Merge branch 'master' into cliffc-gbm4
Clean up GBMTest
Comment change for nbins
Merge branch 'master' of github.com:0xdata/h2o