When someone says LGTM, add LGTM label

When PR status changed, move trello card

When some comment containing mention is posted, the comment request is post to chat service, too.

When new pull request is created, the content of CONTRIBUTING.md is posted as comment.

When some commits is pushed, add 'conflict' label to unmergeable pull request.

Post annotate comment to major/minor version changing at `Gemfile.lock` of pull request.

When you assign Pull request reviewers, it post to chat service too.

When some pull request is labeled, the pull request is notified to chat service.

Prpr plugin to notify when a pull request review is requested, or when a review request is removed

Publish prpr message to slack.