Create PSKs with the correct encoding type

Create PSKs with the correct encoding type

Encoding/decoding code that currently ignores the value of this
field, but this will change when certificates and role features
are merged in.

Change-Id: Idf8d2b1ffd95d2e517e4da7c76ce767a57ce428d
Signed-off-by: Kevin Kane <kkane@microsoft.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/18407
Reviewed-by: Alex Kelley <alexke@microsoft.com>
Reviewed-by: Nathan Heldt-Sheller <nathan.heldt-sheller@intel.com>
Tested-by: jenkins-iotivity <jenkins@iotivity.org>