bump health check :gem: to 0.2.0
Bump jemoji to v0.4.0

Diff: https://github.com/jekyll/jemoji/compare/v0.3.0...v0.4.0
Only important file is lib/jemoji.rb
Release: https://github.com/jekyll/jemoji/releases/tag/v0.4.0
Resolve dependency issues
Merge remote-tracking branch 'origin/health-check-2' into bump-hella-oss-dependencies
Bump to version 30
Merge pull request #108 from github/bump-hella-oss-dependencies

Bump hella oss dependencies
Bump mentions to two-dot-oh
Merge pull request #109 from github/bump-mentions

Bump mentions to two-dot-oh
Add AppVeyor tests for Windows.