sql: clean generation of summary by text
A variety of fixes for sparksql

1.  into list <- SchemaRDD turns Row objects to tuples
2.  IntegerType maps to int64, not int32
3.  Fixed sparksql imports
4.  post_compute on a head term calls collect
5.  into(object, RDD) uses list as intermediary rather than Iterable
    This is more widely supported