core: Do not show domain name for groups

The UI show user name for group, which is just its domain name.
This patch solves this issue.

Change-Id: Ife3bf9e19862ae0cc4462375032a24c62f44b6dc
Bug-Url: https://bugzilla.redhat.com/1072918
Signed-off-by: lzelkha@redhat.com <lzelkha@redhat.com>