Restructure parameter.sanityCheck

Basically, make the sanityCheckers check params as you move down the
hiearchy.  Supervised learner checks basic response-column sanity,
SharedTree learner checks ntrees, etc.
Remove per-algo response-is-classify-or-regression question into the
basic sanity checkers.  Test & external code must toEnum response var
for classification.
Add Vec.isBad
ideaj warning removal
More internal fields get leading unscores
Merge branch 'master' of github.com:0xdata/h2o-dev
Fix odd setup issue

just call H2O.main & H2O.waitForCloudSize
Was setting the stall-till-size==0, then ignoring the
stall_till_cloudsize(5) call.
Turn off non-working test