Statsguru is the rugby statistics database behind ESPN's scrum.com's.Statsguru looks to be the most detailed (matches from 1871), however I'm not sure if they offer bulk download, or if you'll have to scrape it.
RugbyStats.com has stats, but only shows the latest 200 entries, so very recent matches; again, not sure if there's bulk available (seriously doubt it), but you can scrape here too:
StatBunker's Rugby Stats has data going back at least to the 1990s; also not sure about bulk/primed for scraping.
Pick and Go looks solid; stats from every international match beginning in 1871. After searching from start date 1871-01-01 to the year 2015, a table is returned that holds all of that juicy data. So while there's no bulk download, this dataset is the largest (of this list), so scraping it is ideal. For what its worth, this dataset was created for data/statistics consumption.