[IOT-1588] Update cJSON to v1.0.1 and add version tracking note

[IOT-1588] Update cJSON to v1.0.1 and add version tracking note

Added README file that notes the source repository for this
dependency, the commit ID and release tag (where applicable)
used when copying the source files from it, and any local
modifications made.

Change-Id: Ic19b2bcc0cf6e0c2b77906eacb4203a0874dec55
Signed-off-by: Kevin Kane <kkane@microsoft.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/14625
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Dan Mihai <Daniel.Mihai@microsoft.com>
Reviewed-by: Mike Fenelon <mike.fenelon@microsoft.com>
Reviewed-by: Phil Coval <philippe.coval@osg.samsung.com>
(cherry picked from commit 41010a8a4bac41f27c53a4036daf67e6dda87d81)
Reviewed-on: https://gerrit.iotivity.org/gerrit/14767