Merge branch 'activity-links' into 'master'

Fixed issue with activity links not being consistent

## What does this MR do?

Previously, links for opening an issue/merge request & commenting where different. Opening would only have a link on the number whereas commenting would have link on the text as well. This standardises it to include the type as well (ie. issue)

## What are the relevant issue numbers?

Closes #17621 

## Screenshots (if relevant)

![Screen_Shot_2016-06-01_at_12.12.09](/uploads/c778b007e6b6c068fcae30e34409ce98/Screen_Shot_2016-06-01_at_12.12.09.png)

See merge request !4400

app/views/events/event/_common.html.haml

 .event-title
   %span.author_name= link_to_author event
   %span.event_label{class: event.action_name}
-    = event_action_name(event)
-
   - if event.target
-    %strong= link_to event.target.reference_link_text, [event.project.namespace.becomes(Namespace), event.project, event.target], class: 'has-tooltip', title: event.target_title
+    = event.action_name
+    %strong
+      = link_to [event.project.namespace.becomes(Namespace), event.project, event.target], class: 'has-tooltip', title: event.target_title do
+        = event.target_type.titleize.downcase
+        = event.target.reference_link_text
+  - else
+    = event_action_name(event)
   = event_preposition(event)