Updating Gemfile for GitHub Pages

According to [this page](http://jekyllrb.com/docs/github-pages/), our gem file should look like this one to work.
evangelistcollective · May 30, 2015 · 9529caf · 9529caf
1 parent 01cc2c1
commit 9529caf
Showing 1 changed file with 5 additions and 1 deletion.
diff --git a/Gemfile b/Gemfile
@@ -1,3 +1,7 @@
 source 'https://rubygems.org'
-gem 'github-pages'
 
+require 'json'
+require 'open-uri'
+versions = JSON.parse(open('https://pages.github.com/versions.json').read)
+
+gem 'github-pages', versions['github-pages']