Travis: different syntax for Go 1.5 version
Travis: different syntax for Go 1.5 version

rlustin/letsencrypt,piru/letsencrypt,VladimirTyrin/letsencrypt,rlustin/letsencrypt,Hasimir/letsencrypt,hlieberman/letsencrypt,rutsky/letsencrypt,bestwpw/letsencrypt,beermix/letsencrypt,DavidGarciaCat/letsencrypt,jmhodges/letsencrypt,lmcro/letsencrypt,deserted/letsencrypt,VladimirTyrin/letsencrypt,g1franc/lets-encrypt-preview,TheBoegl/letsencrypt,dietsche/letsencrypt,fmarier/letsencrypt,bsmr-misc-forks/letsencrypt,thanatos/lets-encrypt-preview,BKreisel/letsencrypt,dietsche/letsencrypt,bsmr-misc-forks/letsencrypt,hsduk/lets-encrypt-preview,wteiken/letsencrypt,goofwear/letsencrypt,kuba/letsencrypt,sjerdo/letsencrypt,Jadaw1n/letsencrypt,rutsky/letsencrypt,letsencrypt/letsencrypt,xgin/letsencrypt,luorenjin/letsencrypt,armersong/letsencrypt,kevinlondon/letsencrypt,luorenjin/letsencrypt,kevinlondon/letsencrypt,jtl999/certbot,martindale/letsencrypt,fmarier/letsencrypt,Sveder/letsencrypt,Sveder/letsencrypt,riseofthetigers/letsencrypt,BillKeenan/lets-encrypt-preview,TheBoegl/letsencrypt,brentdax/letsencrypt,BKreisel/letsencrypt,mrb/letsencrypt,ghyde/letsencrypt,stweil/letsencrypt,rugk/letsencrypt,martindale/letsencrypt,lbeltrame/letsencrypt,twstrike/le_for_patching,goofwear/letsencrypt,Bachmann1234/letsencrypt,jsha/letsencrypt,jsha/letsencrypt,deserted/letsencrypt,lbeltrame/letsencrypt,mrb/letsencrypt,jtl999/certbot,g1franc/lets-encrypt-preview,BillKeenan/lets-encrypt-preview,wteiken/letsencrypt,hsduk/lets-encrypt-preview,lmcro/letsencrypt,DavidGarciaCat/letsencrypt,thanatos/lets-encrypt-preview,armersong/letsencrypt,tyagi-prashant/letsencrypt,mitnk/letsencrypt,stweil/letsencrypt,jmhodges/letsencrypt,piru/letsencrypt,skynet/letsencrypt,xgin/letsencrypt,beermix/letsencrypt,hlieberman/letsencrypt,sjerdo/letsencrypt,tyagi-prashant/letsencrypt,Jadaw1n/letsencrypt,Bachmann1234/letsencrypt,skynet/letsencrypt,rugk/letsencrypt,ghyde/letsencrypt,bestwpw/letsencrypt,letsencrypt/letsencrypt,brentdax/letsencrypt,Hasimir/letsencrypt,kuba/letsencrypt,mitnk/letsencrypt,twstrike/le_for_patching,riseofthetigers/letsencrypt