Log Message:
Update ruby-jekyll-gist to 1.4.0.

## 1.4.0 / 2015-12-01

  * Allow `noscript` fallback to be disabled (#29)
  * Use Octokit to fetch Gist content when passed `JEKYLL_GITHUB_TOKEN`
    in env(#28)

## 1.3.5 / 2015-10-23

  * Fix encoding error for `noscript` code (#23)
  * Test against Jekyll 3, 2, and the github-pages gem (#19)