Add parameter requirement.
Merge branch 'master' into brandon-word2vec

* master: (62 commits)
  asFactor now works.
  Fix test to point to new MNIST location.
  Add python test for DL on mnist, TODO: Check accuracy. (reproduces h2o's test_NN2_mnist.py)
  Fix error message for no jar file found.
  fix parse.R issues
  work in progess
  Fix the fact that the model-related schemas were not getting pre-registered due to a bug in the Reflections library.  Eliminate two potential startup races on the schema registry.
  export.R roxygen
  Parse should take a list of FrameKey not a list of Frame.
  Added roxygen for h2o.downloadAllLogs.
  Get rid of some startup warnings.  Thanks, Kevin!
  Add stats.
  cosmetic changes
  Re-fix schema registration bootstrapping.
  Move the schema metadata fields which are on every schema instance into their own sub-object for tidiness.
  guts of test went missing, putting them back
  Fix some roxygen documentation bugs that were breaking the roxygen build. Add devtools and roxygen2 package to package list.
  use KeyV1 instead Key
  Tweak to endpointschema Markdown generation to get array-of-schema fields rendered properly.
  Tweak to endpoint Markdown generation to get output rendered.
  ...
Merge branch 'master' into brandon-word2vec

* master:
  Docs tweak.
  all kinds of $<- fixes
  added gbm runit tests
  remove file
  renamed file
  Updated Flow version
as.character support for enum columns.  Creates a new "wrapped" vector that acts like a string vector.
Merge branch 'brandon-word2vec'

* brandon-word2vec:
  as.character support for enum columns.  Creates a new "wrapped" vector that acts like a string vector.
  Add parameter requirement.
Merge branch 'master' of https://github.com/h2oai/h2o-dev

# By Sebastian Vidrio
# Via Sebastian Vidrio
* 'master' of https://github.com/h2oai/h2o-dev:
  demo test for is.factor