Add Closed Issues by Label to Scraper

[jlaura]

We frequently like to look at the types of issues that are being closed and compute some statistics to understand where in the life cycle of a project we are. The osstracker-scraper is currently pulling the standard tags for open issues and a simple raw count for closed issues. I wonder if it is possible to pull the standard issue tags for closed issues as well? This would allow some computation of things like ratio of bugs to enhancements over the project life cycle.

I have never developed in scala. I think that the linked gist should encompass the changes necessary. This extends the IssuesInfo class to include closed issue metrics, make use of the getIssuesStats func to also pull the closed counts via getIssuesLabelStats that does not appear to need any modification.

I am not sure how to further integrate and would rather not submit a 1/2 cooked PR.