Merge branch 'fix-500-admin-projects' into 'master'

Fix 500 error when filtering projects in admin interface

Fixes #1693

See merge request !1200

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