Prevent 500 error when filter projects with push in admin area

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/models/project.rb

@@ -173,7 +173,7 @@ class Project < ActiveRecord::Base
     end
 
     def with_push
-      includes(:events).where('events.action = ?', Event::PUSHED)
+      joins(:events).where('events.action = ?', Event::PUSHED)
     end
 
     def active