add comments to verify_sni_challenge, make nonce be an ascii string
add comments to verify_sni_challenge, make nonce be an ascii string

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