Added warning about OutOfMemoryError and how to fix
Merge branch 'sparkSummit2014' of github.com:databricks/training into sparkSummit2014
Merge branch 'sparkSummit2014' of github.com:databricks/training into sparkSummit2014
Merge branch 'sparkSummit2014' of github.com:databricks/training into sparkSummit2014