use last_occurrence with --since

closes #645

Signed-off-by: Jiri Moskovcak <jmoskovc@redhat.com>
Signed-off-by: Richard Marko <rmarko@redhat.com>
don't show non critical errors in console notification

closes #646

Signed-off-by: Jiri Moskovcak <jmoskovc@redhat.com>
Signed-off-by: Richard Marko <rmarko@redhat.com>