v0.13.0 - Stream results to CSV

As of this release, results endpoints with /csv format uses db.stream_result_by_name() to connect to database for more efficient memory usage. Without streaming, queries returning large result sets require large amounts of memory to both hold the entire result set and perform format conversion. Streaming handles rows and writes them out in batches. Again, only supported for CSV output at this time, as applying Marshmallow formats to JSON outputs while streaming is a harder problem. It's probably a good idea to avoid JSON output for reports expected to return large numbers of rows.