fix for Rooz. he installed graphviz on win7 and h2o couldn't find it. Graphviz is at version 2.30 now.
h2o was looking for version 2.28 also, on 2.30 at least they removed the space between Graphviz and the version number for the folder it's installed into on win7 (don't know about other platforms). As a hack until someone figures out something better, added lookups for 2.28-2.32 version numbers, both with and without the space. no change to linux lookup. Now passes on Rooz's laptop.
Merge branch 'master' of github.com:0xdata/h2o
Merge branch 'master' of github.com:0xdata/h2o
Merge branch 'master' of github.com:0xdata/h2o
bigger heap for test_billion_rows.py (dataset is around 12GB uncompressed)
no aic on gamma