webadmin, userportal: Custom 405 error page

After rhev manager access failure, browser
should not display the "JBoss Web" package version.

Change-Id: I3029915d10f3df830f3040dc1269ac4607e33ac7
Bug-Url: https://bugzilla.redhat.com/1129944
Signed-off-by: Ravi Nori <rnori@redhat.com>