Allow data files whose header in the first line but also start with a # character.
Merge commit '7eb7023673a8547e6bed64af808a4f4b72a563de' into brandon-fixes

* commit '7eb7023673a8547e6bed64af808a4f4b72a563de':
  push a beta_constraints test for tomas
  add beta_constraints to smalldata
  fix beta_constraints name
  h2o.saveAll edited to handle duplicate/xval models
  Updated PDF
  for discussion in https://0xdata.atlassian.net/browse/HEX-1814 gets a write lock exception. Can look at the test and sandbox/commands.log and decide if  you think the h2o architecture is doing what it's designed to do, or if this is a temporal state that might go away in time, or the test is not-supported user behavior. depends on your point of view, I think?
  add Tableau+R demo test
  Update Tableau demo notebook for h2o.ddply instead of ddply.
  clean up of commented out code
  R Vignette edited for structure and R code
  save model check for null xvalmodels in GLM first, fixes null pointer exception