This enables luksrku to terminate if a certain number of broadcast
attempts has failed (usually due to unavailable networking), therefore
enabling a second method of unlocking LUKS disks (e.g., by manually
entering the password on the console).
Can now unlock a specified number of hosts as specified on the command
line (e.g., if you want a luksrku client run indefinitely) and also used
the already implemented blacklisting functionality (i.e., if an
unlocking is unsuccessful, it is retried in 120 seconds, not
immediately, as not to spam servers with illegal credentials).
