Add oEmbed discovery tags to asciicast page

app/presenters/asciicast_page_presenter.rb

@@ -107,6 +107,10 @@ class AsciicastPagePresenter
     author.asciicasts_excluding(asciicast, 3).decorate
   end
 
+  def asciicast_oembed_url(routes, format)
+    routes.oembed_url(url: routes.asciicast_url(asciicast), format: format)
+  end
+
   private
 
   def author

app/views/asciicasts/show.html.slim

@@ -1,4 +1,7 @@
 - content_for(:title, page.title)
+- content_for(:head) do
+  link rel="alternate" type="application/json+oembed" href="#{page.asciicast_oembed_url(self, :json)}"
+  link rel="alternate" type="text/xml+oembed" href="#{page.asciicast_oembed_url(self, :xml)}"
 
 .asciicast-page
   section.cinema

app/views/layouts/application.html.slim

@@ -11,6 +11,7 @@ html[lang="en"]
     = javascript_include_tag "player"
     = favicon_link_tag 'favicon.png'
     = render 'layouts/ga' if Rails.env.production?
+    = content_for(:head)
   body
     = render 'layouts/header'
     = render 'shared/flash'