add contribution footer to all emails

app/views/layouts/_mailer.html.haml

@@ -70,3 +70,19 @@
               You're receiving this email because of your account on
               = succeed "." do
                 %a{ href: root_url, style: "color:#3777b0;text-decoration:none;" }= Gitlab.config.gitlab.host
+
+        - if Gitlab.com?
+          %tr
+            %td{ style: "font-family:'Helvetica Neue',Helvetica,Arial,sans-serif;font-size:13px;line-height:1.6;color:#5c5c5c;" }
+              %div
+                Everyone can contribute
+              %div
+                = link_to 'Blog', 'https://about.gitlab.com/blog/', style: "color:#3777b0;text-decoration:none;"
+                ·
+                = link_to 'Twitter', 'https://twitter.com/gitlab', style: "color:#3777b0;text-decoration:none;"
+                ·
+                = link_to 'Facebook', 'https://www.facebook.com/gitlab/', style: "color:#3777b0;text-decoration:none;"
+                ·
+                = link_to 'YouTube', 'https://www.youtube.com/channel/UCnMGQ8QHMAnVIsI3xJrihhg', style: "color:#3777b0;text-decoration:none;"
+                ·
+                = link_to 'LinkedIn', 'https://www.linkedin.com/company/gitlab-com', style: "color:#3777b0;text-decoration:none;"