Display who added commercial for event

Activate versioning for tests

The tests were failing because of the lack of versioning.By default, versioning is off for tests.
As a result, here (app/views/proposal/_form.html.haml L43) commercial,versions.last returns nil as there are no versions.

app/views/admin/events/show.html.haml

@@ -21,7 +21,7 @@
                   = version.id
                 %td
                   %p
-                    = change_creator_link(version.whodunnit)
+                    = link_to_user(version.whodunnit)
 
                     - if version.item_type == 'Event'
                       = event_change_description(version)