got rid of illegal non-ascending cols case. added more checking
update test_rf_covtype_brutal.py to be able to run with local files with USE_LOCAL inside. didn't test whether I broke the hdfs/s3n case
default to getting files from hdfs/s3n but have internal USE_LOCAL that can be flipped to get files locally (didn't test the hdfs/s3n case)
default to local, with 2 jvms