ASACORE-1134: Allow overridding of the AJ GUID generation for testing purposes

Added new define AJ_CreateNewGUID for the GUID generation function.

The following should be defined in aj_target.h to make sure that a random
GUID is generated at first startup:
    #define AJ_CreateNewGUID AJ_RandBytes

Change-Id: Ida1b847185405bf5ef2f1356a29d03428c0b308e
Signed-off-by: Aaron Pulliam <aaronp@qce.qualcomm.com>
Merge "ASACORE-1134: Allow overridding of the AJ GUID generation for testing purposes"