Replace log level from CRIT to crit in conf/fiaif.conf

The support of upper-case log levels names had been dropped in iptables >= 1.4.15
Older iptables versions can handle both upper and lower case names,
newly ones - only lower case.

--- conf/fiaif.conf
+++ conf/fiaif.conf
@@ -100,7 +100,7 @@ LOG_PREFIX="FIAIF_"
 ##   BURST : Maximum  initial  number  of packets to match: this
 ##           number is incrementedby one every time  the  limit
 ##           specified  above is not reached, up to this number.
-LOG_LEVEL=CRIT
+LOG_LEVEL=crit
 LOG_LIMIT=10/minute
 LOG_BURST=10