[IOT-1582] Change "PUT" to count as "Create" and never as "Update"

[IOT-1582] Change "PUT" to count as "Create" and never as "Update"

Per Core Spec conventions, even though PUT is technically legal
for Create or Update, PUT is only ever used for Create.  Therefore
we need to change the CRUDN permission bit check in security layer.

Updated Readme.scons.txt and README-building-and-running-secure-IoTivity-
stack.txt to clarify build and use of secure IoTivity stack.

Change-Id: Id362c9c0225e53240b2d1f844c5f05d55cfa2938
Signed-off-by: Nathan Heldt-Sheller <nathan.heldt-sheller@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/14579
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Phil Coval <philippe.coval@osg.samsung.com>
Reviewed-by: Kevin Kane <kkane@microsoft.com>
Reviewed-by: Craig Pratt <craig@ecaspia.com>
Reviewed-by: Greg Zaverucha <gregz@microsoft.com>
Reviewed-by: Uze Choi <uzchoi@samsung.com>