Merge branch 'issue-boards' into 'master'

Issue boards

## What are the relevant issue numbers?

- Issue: #17907 
- Issue backend: #20335 
- Backend MR: !5548
- Frontend MR: !5554
- Documentation !5713 

## Screenshots (if relevant)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [X] ~~[Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- [X] ~~API support added~~
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5548

1 files changed, 4 insertions, 0 deletions

diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index c3613bc67dd..f3733b01721 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -320,4 +320,8 @@ module ApplicationHelper
       capture(&block)
     end
   end
+
+  def page_class
+    "issue-boards-page" if current_controller?(:boards)
+  end
 end