Spec compliance change to move oc/core/d to oic/p.

Spec compliance change to move oc/core/d to oic/p.

Moved /oc/core/d to /oic/p.
 -Created a  new struct for platform information.
 -Added code paths so devices can respond to platform discovery query.
 -Added public APIs to registerPlatform used by server devices and
  getPlatformInfo used by client devices. getPlatformInfo is just to make
  the intent of the request clear. Internally, it uses all of the plumbing
  that is already in place for what was previously "device".
 -Changed stack to hold smaller OCPlatfromInfo object compared to a
  cJson object. Construct cjson only when discovery request received and
  delete immediately.

Change-Id: Ie5cca447e8fac67171be5a5ec7c5ece563fbb7ca
Signed-off-by: Mandeep Shetty <mandeep.shetty@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/987
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Erich Keane <erich.keane@intel.com>