Make work package table headers accessible and display them with temporary style (#2264)
Add change log entry (#2264)
Fix selection in integration test...


...after more than one table on work_pakages#show has table headers
Render relations table only if there are related work packages
Show / hide work package relations table after AJAX updates


Fixes integration tests
Merge pull request #810 from opf/accessible-work-package-tables-2264