engine: Locale dropdown not working

- Fixed issue where if you caused a scrollbar to appear
  in the browser, then locale selection dropdown would
  stop working. The css placed the element fixed to then
  browser window instead of relative to the containing
  element
- Fixed the same issue for webadmin and user portal login
  screens.

Change-Id: Id25bb36914c8c2ecdde62fbb04b7b0374be3d88d
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1009986
Signed-off-by: Alexander Wels <awels@redhat.com>