Update status embeds (#4742)

- Use statuses controller for embeds instead of stream entries controller
- Prefer /@:username/:id/embed URL for embeds
- Use /@:username as author_url in OEmbed
- Add follow link to embeds which opens web intent in new window
- Use redis cache in development
- Cache entire embed

app/serializers/oembed_serializer.rb

@@ -21,7 +21,7 @@ class OEmbedSerializer < ActiveModel::Serializer
   end
 
   def author_url
-    account_url(object.account)
+    short_account_url(object.account)
   end
 
   def provider_name
@@ -38,7 +38,7 @@ class OEmbedSerializer < ActiveModel::Serializer
 
   def html
     tag :iframe,
-        src: embed_account_stream_entry_url(object.account, object),
+        src: embed_short_account_status_url(object.account, object),
         style: 'width: 100%; overflow: hidden',
         frameborder: '0',
         scrolling: 'no',