Add cover to Travis CI build matrix
Add cover to Travis CI build matrix

thanatos/lets-encrypt-preview,Hasimir/letsencrypt,riseofthetigers/letsencrypt,g1franc/lets-encrypt-preview,piru/letsencrypt,bsmr-misc-forks/letsencrypt,BillKeenan/lets-encrypt-preview,mrb/letsencrypt,hsduk/lets-encrypt-preview,Jadaw1n/letsencrypt,bestwpw/letsencrypt,vcavallo/letsencrypt,rlustin/letsencrypt,VladimirTyrin/letsencrypt,g1franc/lets-encrypt-preview,rugk/letsencrypt,skynet/letsencrypt,hlieberman/letsencrypt,jmhodges/letsencrypt,beermix/letsencrypt,stweil/letsencrypt,thanatos/lets-encrypt-preview,hsduk/lets-encrypt-preview,mitnk/letsencrypt,TheBoegl/letsencrypt,twstrike/le_for_patching,luorenjin/letsencrypt,jtl999/certbot,vcavallo/letsencrypt,Jonadabe/letsencrypt,mitnk/letsencrypt,digideskio/lets-encrypt-preview,lbeltrame/letsencrypt,martindale/letsencrypt,jsha/letsencrypt,sjerdo/letsencrypt,ruo91/letsencrypt,riseofthetigers/letsencrypt,deserted/letsencrypt,rugk/letsencrypt,hlieberman/letsencrypt,letsencrypt/letsencrypt,lmcro/letsencrypt,ahojjati/letsencrypt,dietsche/letsencrypt,BKreisel/letsencrypt,VladimirTyrin/letsencrypt,lbeltrame/letsencrypt,DavidGarciaCat/letsencrypt,jmhodges/letsencrypt,goofwear/letsencrypt,piru/letsencrypt,fmarier/letsencrypt,stewnorriss/letsencrypt,ghyde/letsencrypt,jmaurice/letsencrypt,tdfischer/lets-encrypt-preview,fmarier/letsencrypt,brentdax/letsencrypt,modulexcite/letsencrypt,jsha/letsencrypt,wteiken/letsencrypt,luorenjin/letsencrypt,kevinlondon/letsencrypt,rutsky/letsencrypt,armersong/letsencrypt,PeterMosmans/letsencrypt,deserted/letsencrypt,tdfischer/lets-encrypt-preview,jmaurice/letsencrypt,Jadaw1n/letsencrypt,tyagi-prashant/letsencrypt,beermix/letsencrypt,Hasimir/letsencrypt,goofwear/letsencrypt,bestwpw/letsencrypt,sjerdo/letsencrypt,letsencrypt/letsencrypt,diracdeltas/lets-encrypt-preview,twstrike/le_for_patching,TheBoegl/letsencrypt,Bachmann1234/letsencrypt,BKreisel/letsencrypt,lmcro/letsencrypt,Jonadabe/letsencrypt,sapics/letsencrypt,wteiken/letsencrypt,Bachmann1234/letsencrypt,xgin/letsencrypt,stewnorriss/letsencrypt,mrb/letsencrypt,solidgoldbomb/letsencrypt,bsmr-misc-forks/letsencrypt,DavidGarciaCat/letsencrypt,diracdeltas/lets-encrypt-preview,tyagi-prashant/letsencrypt,xgin/letsencrypt,BillKeenan/lets-encrypt-preview,jtl999/certbot,dietsche/letsencrypt,stweil/letsencrypt,solidgoldbomb/letsencrypt,ruo91/letsencrypt,PeterMosmans/letsencrypt,brentdax/letsencrypt,Sveder/letsencrypt,kuba/letsencrypt,Sveder/letsencrypt,martindale/letsencrypt,digideskio/lets-encrypt-preview,rlustin/letsencrypt,armersong/letsencrypt,rutsky/letsencrypt,kuba/letsencrypt,ahojjati/letsencrypt,skynet/letsencrypt,sapics/letsencrypt,kevinlondon/letsencrypt,modulexcite/letsencrypt,ghyde/letsencrypt