Use POLICY_LOGS env variable in logging.properties

Use POLICY_LOGS env variable in logging.properties

Some logger.properties have /var/log/onap hard-coded; changed those
to use $POLICY_LOGS.
Other logger.properties had ${POLICY_LOGS} instead of ${{POLICY_LOGS}};
fixed those, too.

Change-Id: I56faf5982abf520ee364b54a3560313d0f15cc2a
Issue-ID: POLICY-784
Signed-off-by: Jim Hahn <jrh3@att.com>