cmd/bosun: don't append :4242 on empty host
cmd/bosun: don't append :4242 on empty host

This matters because on the rule page, we could send an empty tsdbHost.

mhenderson-so/bosun,seekingalpha/bosun,influxdb/bosun,yyljlyy/bosun,treejames/bosun,SlashmanX/bosun,mehulkar/bosun,influxdb/bosun,alienth/bosun,dieface/bosun,youngl98/bosun,mnikhil-git/bosun,mhenderson-so/bosun,eMerzh/bosun,cazacugmihai/bosun,Skyscanner/bosun,influxdb/bosun,jareksm/bosun,alienth/bosun,leapar/bosun,mxk1235/bosun,influxdata/bosun,fisdap/bosun,inkel/bosun,treejames/bosun,azhurbilo/bosun,azhurbilo/bosun,TrentScholl/bosun,eMerzh/bosun,madhukarreddy/bosun,shanemadden/bosun,SlashmanX/bosun,dimamedvedev/bosun,objStorage/bosun,objStorage/bosun,bridgewell/bosun,shanemadden/bosun,mnikhil-git/bosun,eMerzh/bosun,objStorage/bosun,csmith-palantir/bosun,couchand/bosun,GROpenSourceDev/bosun,youngl98/bosun,bosun-sharklasers/bosun,bookingcom/bosun,cazacugmihai/bosun,TrentScholl/bosun,seekingalpha/bosun,seekingalpha/bosun,melifaro/bosun,mnikhil-git/bosun,bosun-monitor/bosun,mathpl/bosun,evgeny-potapov/bosun,bookingcom/bosun,gregdel/bosun,Skyscanner/bosun,bridgewell/bosun,madhukarreddy/bosun,dbirchak/bosun,noblehng/bosun,dieface/bosun,bridgewell/bosun,eMerzh/bosun,bosun-sharklasers/bosun,dbirchak/bosun,cyngn/bosun,gregdel/bosun,fisdap/bosun,mathpl/bosun,simnv/bosun,augporto/bosun,briantist/bosun,bosun-sharklasers/bosun,leapar/bosun,dimamedvedev/bosun,noblehng/bosun,madhukarreddy/bosun,csmith-palantir/bosun,jareksm/bosun,dimamedvedev/bosun,augporto/bosun,inkel/bosun,dimamedvedev/bosun,melifaro/bosun,mxk1235/bosun,mnikhil-git/bosun,snowsnail/bosun,briantist/bosun,bridgewell/bosun,cyngn/bosun,csmith-palantir/bosun,bosun-monitor/bosun,Skyscanner/bosun,dieface/bosun,fisdap/bosun,mhenderson-so/bosun,madhukarreddy/bosun,SlashmanX/bosun,mathpl/bosun,couchand/bosun,snowsnail/bosun,GROpenSourceDev/bosun,fisdap/bosun,trigrass2/bosun,eMerzh/bosun,dbirchak/bosun,leapar/bosun,bosun-monitor/bosun,noblehng/bosun,csmith-palantir/bosun,GROpenSourceDev/bosun,mhenderson-so/bosun,bosun-monitor/bosun,vitorboschi/bosun,noblehng/bosun,CheRuisiBesares/bosun,bridgewell/bosun,jareksm/bosun,melifaro/bosun,TrentScholl/bosun,leapar/bosun,bookingcom/bosun,influxdb/bosun,bosun-sharklasers/bosun,mhenderson-so/bosun,madhukarreddy/bosun,couchand/bosun,mnikhil-git/bosun,yyljlyy/bosun,mehulkar/bosun,trigrass2/bosun,TrentScholl/bosun,gregdel/bosun,simnv/bosun,simnv/bosun,azhurbilo/bosun,alienth/bosun,jareksm/bosun,treejames/bosun,briantist/bosun,gregdel/bosun,bosun-monitor/bosun,snowsnail/bosun,SlashmanX/bosun,dbirchak/bosun,snowsnail/bosun,cyngn/bosun,vitorboschi/bosun,inkel/bosun,mehulkar/bosun,mehulkar/bosun,eMerzh/bosun,seekingalpha/bosun,evgeny-potapov/bosun,youngl98/bosun,CheRuisiBesares/bosun,bosun-sharklasers/bosun,snowsnail/bosun,influxdata/bosun,inkel/bosun,youngl98/bosun,briantist/bosun,evgeny-potapov/bosun,bosun-monitor/bosun,gregdel/bosun,mnikhil-git/bosun,dieface/bosun,evgeny-potapov/bosun,mathpl/bosun,augporto/bosun,dimamedvedev/bosun,influxdb/bosun,Skyscanner/bosun,influxdata/bosun,alienth/bosun,yyljlyy/bosun,jareksm/bosun,SlashmanX/bosun,cyngn/bosun,youngl98/bosun,couchand/bosun,vitorboschi/bosun,fisdap/bosun,influxdata/bosun,trigrass2/bosun,inkel/bosun,leapar/bosun,treejames/bosun,yyljlyy/bosun,dbirchak/bosun,augporto/bosun,GROpenSourceDev/bosun,melifaro/bosun,mxk1235/bosun,objStorage/bosun,bosun-sharklasers/bosun,influxdata/bosun,couchand/bosun,shanemadden/bosun,alienth/bosun,briantist/bosun,azhurbilo/bosun,shanemadden/bosun,trigrass2/bosun,mxk1235/bosun,noblehng/bosun,alienth/bosun,objStorage/bosun,mathpl/bosun,fisdap/bosun,csmith-palantir/bosun,trigrass2/bosun,mathpl/bosun,influxdb/bosun,treejames/bosun,mxk1235/bosun,mehulkar/bosun,TrentScholl/bosun,GROpenSourceDev/bosun,yyljlyy/bosun,noblehng/bosun,azhurbilo/bosun,TrentScholl/bosun,influxdata/bosun,evgeny-potapov/bosun,dieface/bosun,youngl98/bosun,SlashmanX/bosun,bookingcom/bosun,gregdel/bosun,leapar/bosun,trigrass2/bosun,Skyscanner/bosun,shanemadden/bosun,CheRuisiBesares/bosun,vitorboschi/bosun,shanemadden/bosun,bookingcom/bosun,melifaro/bosun,snowsnail/bosun,dimamedvedev/bosun,melifaro/bosun,couchand/bosun,evgeny-potapov/bosun,treejames/bosun,augporto/bosun,inkel/bosun,simnv/bosun,csmith-palantir/bosun,seekingalpha/bosun,CheRuisiBesares/bosun,simnv/bosun,seekingalpha/bosun,Skyscanner/bosun,simnv/bosun,mhenderson-so/bosun,bridgewell/bosun,madhukarreddy/bosun,vitorboschi/bosun,CheRuisiBesares/bosun,cazacugmihai/bosun,mehulkar/bosun,GROpenSourceDev/bosun,cazacugmihai/bosun,mxk1235/bosun,cyngn/bosun,cazacugmihai/bosun,bookingcom/bosun,jareksm/bosun,azhurbilo/bosun,cazacugmihai/bosun,dbirchak/bosun,dieface/bosun,briantist/bosun,vitorboschi/bosun,augporto/bosun,yyljlyy/bosun,CheRuisiBesares/bosun,objStorage/bosun,cyngn/bosun