Modest Changes to the organization of EOS.IO Github issues

Heads up if you're tracking the EOS.IO Github -- yesterday we rationalized the mapping of issues to milestones, reflecting that our work is now proceeding in two tracks, as well as our go-forward standard of only placing an issue in a milestone when it clears testing at the end of a sprint. We've also completed setup of sync between Jira and Github, so we moved some Github issues to new issue numbers as a side effect. (You'll see our Jira ticket numbers as a prefix in the Github issue title.)