Change pstat.deviceuuid from R-only to RW

Change pstat.deviceuuid from R-only to RW

As SWG decided that pstat.deviceuuid is RW,
pstat handler has been fixed accordingly.

Patch #1: Initial upload

Change-Id: Ibc0b1d86ddfb06306268dddaf07f38152d8800f2
Signed-off-by: Jongmin Choi <jminl.choi@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/14069
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Kevin Kane <kkane@microsoft.com>
Reviewed-by: Nathan Heldt-Sheller <nathan.heldt-sheller@intel.com>
Reviewed-by: Uze Choi <uzchoi@samsung.com>
Reviewed-by: Randeep Singh <randeep.s@samsung.com>