dnsbl: make zones list unique, which it might not be
dnsbl: make zones list unique, which it might not be

if you have zones listed in dnsbl.ini and (b/c of boolean bug) and also in dnsbl.zones, they will be merged instead of concatenated.

niteoweb/Haraka,jaredj/Haraka,DarkSorrow/Haraka,msimerson/Haraka,fatalbanana/Haraka,slattery/Haraka,AbhilashSrivastava/haraka_sniffer,hiteshjoshi/my-haraka-config,zombified/Haraka,Dexus/Haraka,typingArtist/Haraka,smfreegard/Haraka,smfreegard/Haraka,MignonCornet/Haraka,MignonCornet/Haraka,danucalovj/Haraka,bsmr-x-script/Haraka,smfreegard/Haraka,DarkSorrow/Haraka,zombified/Haraka,hatsebutz/Haraka,haraka/Haraka,Dexus/Haraka,niteoweb/Haraka,jaredj/Haraka,Synchro/Haraka,slattery/Haraka,msimerson/Haraka,AbhilashSrivastava/haraka_sniffer,Dexus/Haraka,danucalovj/Haraka,jjz/Haraka,zombified/Haraka,zombified/Haraka,jjz/Haraka,msimerson/Haraka,baudehlo/Haraka,niteoweb/Haraka,fatalbanana/Haraka,slattery/Haraka,DarkSorrow/Haraka,AbhilashSrivastava/haraka_sniffer,bsmr-x-script/Haraka,abhas/Haraka,Synchro/Haraka,MignonCornet/Haraka,fatalbanana/Haraka,danucalovj/Haraka,craigslist/Haraka,typingArtist/Haraka,hiteshjoshi/my-haraka-config,fatalbanana/Haraka,Synchro/Haraka,Synchro/Haraka,bsmr-x-script/Haraka,abhas/Haraka,baudehlo/Haraka,craigslist/Haraka,bsmr-x-script/Haraka,smfreegard/Haraka,Dexus/Haraka,jaredj/Haraka,haraka/Haraka,msimerson/Haraka,hatsebutz/Haraka,abhas/Haraka,baudehlo/Haraka,jaredj/Haraka,jjz/Haraka,slattery/Haraka,baudehlo/Haraka,typingArtist/Haraka,craigslist/Haraka,typingArtist/Haraka,haraka/Haraka,haraka/Haraka,jjz/Haraka,craigslist/Haraka,hatsebutz/Haraka,hiteshjoshi/my-haraka-config,DarkSorrow/Haraka,AbhilashSrivastava/haraka_sniffer,MignonCornet/Haraka,danucalovj/Haraka,hatsebutz/Haraka