Clean crypto_util, add some doc
Clean crypto_util, add some doc

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