check: handle notifications in sighup

sighup handler now respects quorum_up, quorum_down,
notify_up, notify_down, alpha, omega, quorum, hysteresis
configuration directives
VS_ISEQ: compare quorum_up handler values

This ensures that if quorum_up action has been changed,
it will be instantly called even if service is already UP.
In this case the service will be completely removed and applied
again as a new one.
fix inaccuracy in VS_ISEQ macro

* double check of sched field
* compilation warning (boolean operator precedence)
Merge pull request #31 from andriyanov/sighup

better SIGHUP support in checker daemon