core: Replace log4j with slf4j in branding

Replaces log4j with slf4j in branding module.

Change-Id: I8367326c229fe9eaee18258c2a477507958c3ad4
Bug-Url: https://bugzilla.redhat.com/1109871
Signed-off-by: Martin Perina <mperina@redhat.com>