tools: Replace log4j with JUL as backend for notifier

Replaces log4j with java.util.logging as logging backend in
notifier.

Change-Id: I10216f8530e23c43942cdf28fe2cb306d7e6df71
Bug-Url: https://bugzilla.redhat.com/1109871
Signed-off-by: Martin Perina <mperina@redhat.com>