test: adapt for private repositry check
chore(package): update lockfile https://npm.im/greenkeeper-lockfile
fix: listen for "pull_request.(un)labeled" events (wip#50)
fix(package): probot@^5.0.1
feat: support labels (wip#46)
feat: detect WIP commit messages (wip#32) thanks @Raul6469 & @HeeL
feat: also block 'do not merge' titles (wip#28)
fix: set status target URL to GitHub App page