BIGTOP-1535.  Add Spark ETL script to BigPetStore.
BIGTOP-1544.  User of java.io.File and check for dir existence will fail ith non-POSIX DFS(HDFS, S3, etc)..

Signed-off-by: jayunit100 <jay@apache.org>
BIGTOP-1545.  Bump version of BPS data generator library to 0.2.1

Signed-off-by: jayunit100 <jay@apache.org>