Initial commit of IPCA.

Initial commit of IPCA.

IPCA stands for IoTivity Procedural Client Api, which implements C APIs
for accessing IoTivity RESTful CRUDN APIs.

IPCA uses the C++ APIs provided by OCPlatform and OCResource.
It is intended to be used by application developers, or by code
generated from swagger, to develop IoTivity client apps.

IPCA supports APIs for Discovery of IoTivity devices, Create, Delete
and Observe resources, Get and Set property values, and security
related APIs for password display (typically used in Onboarding
Tool case) and password input (typically used in Multiple Ownership
Transfer case).

Please find more info in: https://wiki.iotivity.org/ipca.
And more info in code:
inc\IPCA.h for API documentation.
src for the implementation of IPCA.
samples\ElevatorClient for sample application that uses the IPCA api.
samples\ipcaapp for sample application that discovers any IoTivity
devices on the network.

Change-Id: I683b02786d4df32b2feacdd9f1674350214b0618
Signed-off-by: Soemin Tjong <stjong@microsoft.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/17449
Tested-by: jenkins-iotivity <jenkins@iotivity.org>
Reviewed-by: Dan Mihai <Daniel.Mihai@microsoft.com>