Set contact address in about/more as mailto link (#4450)

* Set contact address as mailto link

To be able to copy long email address

* Set style for mailto link

app/javascript/styles/about.scss

@@ -147,9 +147,10 @@
       white-space: nowrap;
       overflow: hidden;
 
-      span {
+      a {
         font-weight: 400;
         color: lighten($ui-base-color, 34%);
+        text-decoration: none;
       }
     }
   }

app/views/about/_contact.html.haml

@@ -2,7 +2,7 @@
   .panel-header
     = succeed ':' do
       = t 'about.contact'
-    %span{ title: contact.site_contact_email.presence }= contact.site_contact_email.presence
+    = mail_to contact.site_contact_email.presence, nil, :title => contact.site_contact_email.presence
   .panel-body
     - if contact.contact_account
       .owner