Implement whitelist to eliminate 403 Forbidden errors in IE8

Created a whitelist of all known 403 Forbidden errors occurring in IE8 that are caused by IE8 not passing the referer on redirects. 

https://bugzilla.redhat.com/show_bug.cgi?id=1125380
https://bugzilla.redhat.com/show_bug.cgi?id=1123494
https://bugzilla.redhat.com/show_bug.cgi?id=1087539
@Fryguy, agreed with the frozen constant.  I disagree with the location though, this is only a factor when referer_valid? would have returned false.  I think the soon-to-be-created constant should be located in this file which is the only place it should ever be referenced.