[IOT-1626] Added BSD 3-Clause License in SCons.

[IOT-1626] Added BSD 3-Clause License in SCons.

Because SCons has dual license.

From https://github.com/flashpixx/Storage/tree/master/Scons

Change-Id: If45a359bb41efb3bdd93d33d20e6d26ec28847c5
Signed-off-by: Jaehong Jo <jaehong.jo@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/14951
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Dan Mihai <Daniel.Mihai@microsoft.com>
Reviewed-by: Hyuna Jo <hyuna0213.jo@samsung.com>
Reviewed-by: Phil Coval <philippe.coval@osg.samsung.com>