ALLJOYN-2335 Check CRC before interpreting header bytes.

Change-Id: Ie1ff010ae5543e96b0f9deda2272e6140cea8674
ALLJOYN-2373 Fix race condition in IODispatch that caused exit alarms to not be added when streams were stopped close in time.

Change-Id: Ib0dc670c4971ae6ddaf2d7548060e01117c7f09b