implemented support for recovery_time_delay

There is a new command line option --recovery-time-delay=VALUE
(short -r) with a mandatory argument (time atom, e.g. 5m or 1h).
If given the generated recovery.conf will contain
recovery_time_delay = VALUE
fixed typo
added validation of parameter

Now parameter gets validated for a valid integer with a valid time atom,
e.g. 5m is no longer possible