Merge branch 'grouped-builds-arrow' into 'master'

Fix overflow to show grouped builds arrow

## What does this MR do?
Removes overflow style so that the arrow shows up again

## Screenshots (if relevant)
Before:   
![Screen_Shot_2016-10-11_at_9.11.55_AM](/uploads/92d2a0c34d2af050e58468c8d61f4cd3/Screen_Shot_2016-10-11_at_9.11.55_AM.png)
After:   
![Screen_Shot_2016-10-11_at_9.11.41_AM](/uploads/2c4c422a21fb6450d00ae638aef29d89/Screen_Shot_2016-10-11_at_9.11.41_AM.png)
Scrolling:   
![Screen_Shot_2016-10-11_at_9.40.36_AM](/uploads/e5b1e3125d881c5882cf199026110d48/Screen_Shot_2016-10-11_at_9.40.36_AM.png)

See merge request !6808

app/assets/stylesheets/pages/pipelines.scss

@@ -420,8 +420,11 @@
         left: auto;
         right: -197px;
         top: -9px;
-        max-height: 245px;
-        overflow-y: scroll;
+
+        ul {
+          max-height: 245px;
+          overflow: auto;
+        }
 
         a {
           color: $gl-text-color;

app/views/projects/commit/_pipeline_status_group.html.haml

@@ -5,8 +5,9 @@
   %span.ci-status-text
     = name
   %span.badge= subject.size
-%ul.dropdown-menu.grouped-pipeline-dropdown
-  %li.arrow
-  - subject.each do |status|
-    %li
-      = render "projects/#{status.to_partial_path}_pipeline", subject: status
+.dropdown-menu.grouped-pipeline-dropdown
+  .arrow
+  %ul
+    - subject.each do |status|
+      %li
+        = render "projects/#{status.to_partial_path}_pipeline", subject: status