check .travis.yml ruby verison matches pages

https://github.com/github/choosealicense.com/pull/472#issuecomment-270048688

very rough, naive, probably bad implementation

spec/ci_ruby_version_spec.rb

@@ -0,0 +1,21 @@
+require 'json'
+require 'open-uri'
+require 'spec_helper'
+require 'yaml'
+
+describe 'ci ruby version' do
+  pages_versions = JSON.parse(open('https://pages.github.com/versions.json').read)
+  pages_ruby_version = pages_versions['ruby']
+
+  ci_config_file = '.travis.yml'
+
+  ci_config = YAML.load_file(ci_config_file)
+  ci_ruby_version = ci_config['rvm'][0]
+
+  context "#{ci_config_file} and pages ruby versions" do
+    it 'do not match' do
+      msg = "(#{ci_ruby_version}) != (#{pages_ruby_version})"
+      expect(ci_ruby_version).to eql(pages_ruby_version), msg
+    end
+  end
+end