[SPARK-2710] [SQL] Build SchemaRDD from a JdbcRDD with MetaData

SPARK-2710 Build SchemaRDD from a JdbcRDD with MetaData

and a small bug fix on JdbcRDD, line 109
it seems conn will never be closed


Yeah, I agree.  I was annoyed when I had to work around this.  As long as its backwards compatible I'm okay including it here.