Upgrade vendored assets to CodeMirror 3.17
Bump gem version for release
Upgrade vendored assets to CodeMirror 3.18
Bump gem version for release
Upgrade vendored assets to CodeMirror 3.19
Bump gem version for release
Upgrade vendored assets to CodeMirror 3.20
Bump gem version for release
Upgrade vendored assets to CodeMirror 3.21
Bump gem version for release