CRED payload conversion from JSON to CBOR

CRED payload conversion from JSON to CBOR

Converts CRED payload from JSON to CBOR directly using tinycbor library.
- CRED unit test has been updated to handle the changes.
- Unit test related functions are defined in security_internals.
- Parameter which were passed as char * has been converted to uint8_t as they were later converted to base64.
- All the usage and base64 has been removed.

Change-Id: I159d46f8500c1880b49a3acbcfc59cfa0c6da4f0
Signed-off-by: Habib Virji <habib.virji@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/5117
Reviewed-by: Randeep Singh <randeep.s@samsung.com>
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-on: https://gerrit.iotivity.org/gerrit/5793