Correct encoding of ZoneIDs in URIs, as per RFC 6874

Correct encoding of ZoneIDs in URIs, as per RFC 6874

IoTivity already included the ZoneID in the URI when the
IPv6 socket address included that information, but failed
to properly encode the percent sign.

Change-Id: I3e1c5b0a267236b1187303430d1dd4f115d1332a
Signed-off-by: David Antler <david.a.antler@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/9419
Reviewed-by: Dave Thaler <dthaler@microsoft.com>
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Jon A. Cruz <jon@joncruz.org>