core : Duplicated login events

Duplicate login events are show on user
login. The first login event is from
webadmin and the second is from plugin
infrastructure.

Change-Id: I7c24a82342d3d6315b7da6aa22e23b6cc594eb68
Bug-Url: https://bugzilla.redhat.com/1026389
Signed-off-by: Ravi Nori <rnori@redhat.com>