* To find the oldest and newest quantities
for calculating rate, Spark Data Frame
is converted to a Spark RDD, which makes it
easy to do a group by and sort. The syntax to pull
the value from a map column type in an
RDD is rdd.map_column['key'] which
is different from dataframe.map_column.key
which was causing 'dict' object has no attribute
* Renamed first_attempt_at_spark_test.py to
test_first_attempt_at_spark, because all the tests
in that file were not being run.
* Changed the pre transform and transform specs
which were being used by test_first_attempt_at_spark
to newer 'dimensions#field_name that was introduced
in rocky release.