Basic port of PCA to h2o-dev.
Merge branch 'brandon-PCA'

* brandon-PCA:
  Basic port of PCA to h2o-dev.
Files left out of earlier checkin.
Merge branch 'master' of https://github.com/h2oai/h2o-dev

# By Patrick Aboyoun
# Via Patrick Aboyoun
* 'master' of https://github.com/h2oai/h2o-dev:
  Clean up edicts in R.
  Cleanup export code in R package.