Set Last-Modified header

lib/remote_storage/riak.rb

@@ -30,6 +30,7 @@ module RemoteStorage
     def get_data(user, category, key)
       object = data_bucket.get("#{user}:#{category}:#{key}")
       headers["Content-Type"] = object.content_type
+      headers["Last-Modified"] = object.last_modified.to_s(:rfc822)
       case object.content_type
       when "application/json"
         return object.data.to_json

spec/permissions_spec.rb

@@ -38,6 +38,8 @@ describe "Permissions" do
 
         last_response.status.must_equal 200
         last_response.body.must_equal "some text data"
+
+        last_response.headers["Last-Modified"].wont_be_nil
       end
     end
   end