Merge branch 'btn-group-secure-group-dashboard' into 'master'

Backport button style changes to CE

See merge request gitlab-org/gitlab-ce!24609

app/assets/stylesheets/framework/buttons.scss

@@ -42,6 +42,10 @@
   color: $text;
   border-color: $border;
 
+  &.btn-border-color {
+    border-color: $border-color;
+  }
+
   > .icon {
     color: $text;
   }