Port preload option to HTML5 element

app/helpers/asciicasts_helper.rb

@@ -17,6 +17,7 @@ module AsciicastsHelper
       speed: options.speed,
       autoplay: options.autoplay,
       loop: options.loop,
+      preload: options.preload,
       'start-at' => options.t,
       'font-size' => options.size,
       theme: options.theme,

app/models/embed_playback_options.rb

@@ -1,3 +1,4 @@
 class EmbedPlaybackOptions < PlaybackOptions
   attribute :autoplay, Boolean, default: false
+  attribute :preload,  Boolean, default: false
 end

app/presenters/bare_asciicast_page_presenter.rb

@@ -6,8 +6,7 @@ class BareAsciicastPagePresenter
     decorated_asciicast = asciicast.decorate
 
     playback_options = {
-      'theme' =>  decorated_asciicast.theme_name,
-      'preload' => false
+      'theme' =>  decorated_asciicast.theme_name
     }.merge(playback_options)
 
     new(decorated_asciicast, EmbedPlaybackOptions.new(playback_options))