Fix #86: Ensure that run/tasks are run at least once per runlevel

This patch fixes the problem with run/task jobs with conditions, run at
runlevel S (bootstrap), not being given enough time to actually start
and run even once.

The new svc counter 'once' is now inspected before transitioning away
from runlevel S to the configured runlevel.  A global (currently hard
coded) timeout of 10 sec is given to all run/tasks.

As a spin-off, this patch starts up the event loop much earlier than
before.  Meaning the initial runlevel change at boot is now done in
a finalize() callback when all run/tasks have completed, or when the
global timeout has expired.  Starting the event loop earlier gives us
the possibility to rely on the pidfile plugin to provide our run/tasks
with the conditions necessary to start.

TODO: What remains is to add similar handling to all runlevel
      transitions, not just the initial one at boot.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

src/service.h

@@ -37,6 +37,8 @@ void      service_reload_dynamic (void);
 void      service_step           (svc_t *svc);
 void      service_step_all       (int types);
 
+void      service_bootstrap_cb   (uev_t *w, void *arg, int events);
+
 #endif	/* FINIT_SERVICE_H_ */
 
 /**