Make hadoop build OS agnostic

Pass in file/path SEP variable to makefiles.
Do not use softlinks, especially pulled from GIT to windoze.
Merge branch 'master' of github.com:0xdata/h2o
Turn off GBM tests
Add ByteVec to the inital list
GBMTest: abort if large file is missing

Also return null from TestUtil if file is missing, instead of a non-null
but missing filename.
Must install H2O R package to run demo
Merge branch 'master' of https://github.com/0xdata/h2o
some parse/summary/inspect of some airline datasets in the s3 h2o-airlines-unpacked bucket
will run in nightly by being in testdir_hosts (on 5 machine ec2 cluster)
Merge branch 'master' of github.com:0xdata/h2o
updated for airline ec2 testing
fails on allyears.csv. summary. npe. first does airlines2k ok.
update