Add more data to the results.csv

[digitaldogsbody]

To aid in analysing the generation process + producing stats and metrics etc, it would be good to include more data in the results CSV file such as:

• Columns for each regeneration of a given month so we could look at how the thresholds are working without needing to crawl through the logs
• Split of registered/findable records for each month (see Separate count of findable records from total record count #16)
• Time taken for generation

We should also timestamp the CSV filename so we can compare across months rather than overwriting each month

[digitaldogsbody]

As of 0.4.1 the results csv includes registered and findable counts. The rest of the stuff here is nice but not critical so pushing back to the backlog