engine: Hosts SearchBox doesn't filter correctly

Hosts - SearchBox "Host:user.usrname =*" doesn't filter correctly

Change-Id: I420b7705596335b9be6d6d8374a11f7542a03db9
Bug-Url: https://bugzilla.redhat.com/1006231
Signed-off-by: Ravi Nori <rnori@redhat.com>