Add tab for readme and load readme in tab.

app/views/projects/show.html.haml

 = render "home_panel"
 
+- readme = @repository.readme
 %ul.nav.nav-tabs
   %li.active
-    = link_to project_path(@project) do
+    = link_to '#tab-activity', 'data-toggle' => 'tab' do
       Activity
+  - if readme
+    %li
+      = link_to '#tab-readme', 'data-toggle' => 'tab' do
+        Readme
   .project-home-links
     - unless @project.empty_repo?
       = link_to pluralize(number_with_delimiter(@repository.commit_count), 'commit'), project_commits_path(@project, @ref || @repository.root_ref)
@@ -11,7 +16,9 @@
       = link_to pluralize(number_with_delimiter(@repository.tag_names.count), 'tag'), project_tags_path(@project)
       %span.light.prepend-left-20= repository_size
 
-.row
+.tab-content
+  .tab-pane.active#tab-activity
+    .row
       %section.col-md-9
         = render "events/event_last_push", event: @last_push
         = render 'shared/event_filter'
@@ -37,11 +44,6 @@
             = link_to project_compare_index_path(@project, from: @repository.root_ref, to: @ref || @repository.root_ref), class: 'btn btn-block' do
               Compare code
 
-        - if @repository.readme
-          - readme = @repository.readme
-          = link_to project_blob_path(@project, tree_join(@repository.root_ref, readme.name)), class: 'btn btn-block' do
-            = readme.name
-
             - if @repository.version
               - version = @repository.version
               = link_to project_blob_path(@project, tree_join(@repository.root_ref, version.name)), class: 'btn btn-block' do
@@ -65,3 +67,14 @@
             %hr
             = link_to @project.gitlab_ci_service.builds_path do
               = image_tag @project.gitlab_ci_service.status_img_path, alt: "build status"
+
+  - if readme
+    .tab-pane#tab-readme
+      %article.readme-holder#README
+        = link_to project_blob_path(@project, tree_join(@repository.root_ref, readme.name)) do
+          %h4.readme-file-title
+            %i.icon-file
+            = readme.name
+        .wiki
+          = render_readme(readme)
+