add referer prop

app/views/posts/index.html.erb

@@ -82,7 +82,8 @@
     $(function() {
       window.Danbooru.mixpanelEvent("Post Search", {
         "tags": <%= params[:tags].to_json %>,
-        "page": <%= params[:page].to_json %>
+        "page": <%= params[:page].to_json %>,
+        "referer": <%= request.referer.to_json %>
       });
     });
   </script>

app/views/posts/show.html.erb

@@ -201,7 +201,8 @@
         "size": <%= @post.file_size %>,
         "fav_count": <%= @post.fav_count %>,
         "created_at": <%= @post.created_at.strftime('%F %T').to_json %>,
-        "tags": <%= @post.presenter.humanized_essential_tag_string.to_json %>
+        "tags": <%= @post.presenter.humanized_essential_tag_string.to_json %>,
+        "referer": <%= request.referer.to_json %>
       });
     });
   </script>