Add readme title and check for rich_viewer

app/views/projects/_readme.html.haml

-- if readme = @repository.readme
+- if (readme = @repository.readme) && (readme.rich_viewer)
   %article.file-holder.readme-holder{ id: 'readme', class: ("limited-width-container" unless fluid_layout) }
+    .js-file-title.file-title
+      = blob_icon readme.mode, readme.name
+      = link_to project_blob_path(@project, tree_join(@ref, readme.path)) do
+        %strong
+          = readme.name
     = render 'projects/blob/viewer', viewer: readme.rich_viewer, viewer_url: namespace_project_blob_path(@project.namespace, @project, tree_join(@repository.root_ref, readme.path), viewer: :rich, format: :json)
 
 - else