Small UI change to milestone page so it looks similar to issue/mr

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Fix admin user errors ui

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Fix UI for wiki error message

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Merge branch 'milestome-ui' into 'master'

Improve Milestome UI

Milestone UI header was different from Issue/MR pages but use same UI elements.
This MR fixes it so UI looks same for issue/mr/milestone
Merge branch 'small-ui-improvements' into 'master'

Small ui improvements

* fix ugly errors block when admin save invalid user
* fix ugly errors when you tries to save invalid wiki page