Update Ansible documentation (2.4.0)

Fixes #677.

lib/docs/filters/ansible/clean_html.rb

@@ -4,6 +4,10 @@ module Docs
       def call
         @doc = at_css('#page-content')
 
+        css('.__cf_email__').each do |node|
+          node.replace(decode_cloudflare_email(node['data-cfemail']))
+        end
+
         doc
       end
     end

lib/docs/scrapers/ansible.rb

@@ -2,8 +2,8 @@ module Docs
   class Ansible < UrlScraper
     self.name = 'Ansible'
     self.type = 'sphinx'
-    self.release = '2.3.1'
-    self.base_url = 'https://docs.ansible.com/ansible/'
+    self.release = '2.4.0'
+    self.base_url = 'https://docs.ansible.com/ansible/latest/'
     self.links = {
       home: 'https://www.ansible.com/',
       code: 'https://github.com/ansible/ansible'