Make file attachment on MediaAttachment optional (#1865)

Create MediaAttachment but without actual file download when domain is blocked with reject_media set to true
Clean up old media files when creating a new domain block with reject_media set to true
Return remote_url in media attachments API if local file is not present
Undo domain block action in admin UI
Ability to enable reject_media from admin UI

spec/views/stream_entries/show.html.haml_spec.rb

@@ -61,5 +61,4 @@ describe 'stream_entries/show.html.haml' do
     expect(mf2.entry.in_reply_to.format.author.format.name.to_s).to eq alice.display_name
     expect(mf2.entry.in_reply_to.format.author.format.url.to_s).not_to be_empty
   end
-
 end