Merge branch 'master' of https://github.com/tootsuite/mastodon

# Conflicts:
#	app/controllers/settings/exports_controller.rb
#	app/models/media_attachment.rb
#	app/models/status.rb
#	app/views/about/show.html.haml
#	docker_entrypoint.sh
#	spec/views/about/show.html.haml_spec.rb

app/presenters/instance_presenter.rb

@@ -48,4 +48,8 @@ class InstancePresenter
   def thumbnail
     @thumbnail ||= Rails.cache.fetch('site_uploads/thumbnail') { SiteUpload.find_by(var: 'thumbnail') }
   end
+
+  def hero
+    @hero ||= Rails.cache.fetch('site_uploads/hero') { SiteUpload.find_by(var: 'hero') }
+  end
 end