Update jekyll conf. New post w/ assets.

Gemfile

@@ -1,2 +1,7 @@
 source 'http://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']