Bug fix for AIStateMachine.

When a state machine is aborted after it switched to bs_initialize,
but before it executed initialize_impl(), then we should set the
state back to bs_reset and abort cleanly by switching to bs_killed
and then handle that. Before the state was set to bs_abort, resulting
in calling abort_impl(), finish_impl(), the call back and unref()
for an not initialized state machine! (detected by the assert that
makes sure that ref()/unref() are called in balance).