Reload HA configuration when policy is changed.

After policy is changed make sure that HA configuration is reloaded.
This is needed by the cf-serverd as we don't want to restart it all
the time HA configuration is changed.
Having it within a lock pertinent to HA's config is, of course, sensible; having it within cf-serverd's thread-management lock is, however, Not A Good Thing, as it's a potentially time-consuming operation (reading a file from a disk); and potentially a Very Dangerous Thing if you also lock some HA-related lock, that might cause a deadlock if something else is holding the HA lock but waiting for the serverd thread-lock.