High: fix stonith ignoring its own messages on heartbeat

Since the introduction of the additional F_TYPE messages
T_STONITH_NOTIFY and T_STONITH_TIMEOUT_VALUE, and their use as message
types in global heartbeat cluster messages, stonith-ng was broken on the
heartbeat cluster stack.

When delegation was made the default, and the result could only be
reaped by listening for the T_STONITH_NOTIFY message, no-one (but
stonithd itself) would ever notice successful completion,
and stonith would be re-issued forever.

Registering callbacks for these F_TYPE fixes these hung stonith and
stonith_admin operations on the heartbeat cluster stack.