userportal,webadmin: close button

- Removed a lot of the z-index changes and reverted to
  letting the browser figure it out. This solves all the
  following:
  - Unable to drag windows
  - Unable to close windows with X
  - Unable to click help icon.

Change-Id: I990250c45783b3ba00ea7ee74d88e2bf6205f2f6
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1150050
Signed-off-by: Alexander Wels <awels@redhat.com>