Medium: stonith: Allow clients to avoid use of Glib mainloop.

Allow an application to avoid use of the Glib mainloop by polling
on the asyncronous file descriptor provided in the connect call.
Activity is then handled by using the newly provided dispatch api
routine, whcih calls stonith_dispatch().

Mercurial revision: 953e87b248b248c455e46f8a02f5a63efcfcaf50