RDServer discovery functionality

RDServer discovery functionality

1. rd_server.h defines three API's.
- API to start a RD server
- API to stop a RD server and clean up

2. rd_payload.h includes API's to create CBOR payload
(has few additions in cstack to support the functionality).

3. rd_types.h defines various different types used to represent
RD structure in payload and internally on the RD server.

4. rd_server.c
- includes functionality to start and stop a RD server
- initializes resource /oic/rd?rt="oic.wk.rd"
- handles discover message from the RD client.
- Discover responds with the biasFactor (currently hardcoded)

5. rd_payload.c contains all functionality for handling CBOR payload.

6. resource/csdk/SConscript
- Includes resource directory in cstack as library if build with WITH_RD

7. octypes.h
- Adds CT_ADAPTER_SHIFT for 32 bit and 16 bit. Previous value of 10 does not work for 32 bit.
- Add PAYLOAD_TYPE_RD in OCPayloadType.

8. ocpayload/ocpayloadconvert/ocpayloadparse
- Payload parsing, converting and destoy for the RD packet

9. Added entry to generate docs for the resource directory.

Change-Id: I699636d386bea829b65339c6dff24abcb056e9b8
Signed-off-by: Habib Virji <habib.virji@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/2155
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>