Update ruby-jekyll-gist to 1.3.4.

## 1.3.4 / 2015-08-28

  * Catch `TimeoutError` to further support 1.9.3 (#16)

## 1.3.3 / 2015-08-20

  * Fix gemspec to allow Ruby 1.9.3 (relates to #14)

## 1.3.2 / 2016-08-19

  * Re-add support for Ruby 1.9.3. Fixes #11 for 1.9.3 (#14)
  * Replaced `OpenURI` with `Net::HTTP` and introduced timeout of 3 seconds (#11)

## 1.3.1 / 2015-08-16 (yanked)

  * Replaced `OpenURI` with `Net::HTTP` and introduced timeout of 3 seconds (#11)

## 1.3.0 / 2015-08-05

  * Added an `noscript` fallback for browsers without JavaScript enabled. (#7)

(taca)