Better guard against calling methods on nil in OctocatHerder::PullRequest
Better guard against calling methods on nil in OctocatHerder::PullRequest

When attempting to retrieve the needed information in
 #merged_by_login, #merged_by_id, #merged_by_avatar_url, and
 #merged_by_url, we were assuming that the pull request had been
merged.  Now we check to see if it has been merged before retrieving
the needed information.

jasoncodes/octocat_herder