Merge pull request #33 from ledell/master

New h2o.ensemble example, wrapper function updates and bug fixes.
Updated sparse chunks to cache offset to avoid the binary search in case of sequential access of nonzero values.
Updated Matrix multiplication to use version which does transpose first, plus added throttling of parallelism (got OOM otherwise).
Request rollups for all columns  in parallel after parse to avoid sequential acces.
Added job and some stats to matrix multiply.
Added rebalance and replace method to rebalance dataset.
changed my json config file.
Corrected typos
Merge branch 'master' of https://github.com/0xdata/h2o
Some additional proofreading changes
fix remnants of VA json elements in some little-run tests
fix little things that showed up testing with Jeff's cloud stuff
try/except an ip case that was failing on jeff's mac
Added Matrix multiply to gui (useful since R has issues handling too many columns)
Fixed sparse interface of constant chunks.
Added third and much more efficient method for sparse matrix multiply, removed the previous two.
Fixed errors
Merge branch 'master' of https://github.com/0xdata/h2o
Fixed redirect after matrix multiplication is done.
Removed accidental import which was failing Jenkins build
Matrix multiplication cleanup.