Refactor Core handlers and add error messages for handlers
Refactor Core handlers and add error messages for handlers

Signed-off-by: Sean Kelly <8edac9b47f7eed28d68690a773aedaa31126c248@imgtec.com>

DavidAntliff/AwaLWM2M,FlowM2M/AwaLWM2M,DavidAntliff/AwaLWM2M,FlowM2M/AwaLWM2M,FlowM2M/AwaLWM2M,DavidAntliff/AwaLWM2M,DavidAntliff/AwaLWM2M,FlowM2M/AwaLWM2M