Randomize serial numbers of DVSNI challenge certs. Should now work on python 2.7 and 3.3+
Randomize serial numbers of DVSNI challenge certs.
Should now work on python 2.7 and 3.3+

lmcro/letsencrypt,jsha/letsencrypt,lmcro/letsencrypt,stweil/letsencrypt,letsencrypt/letsencrypt,letsencrypt/letsencrypt,jtl999/certbot,jsha/letsencrypt,bsmr-misc-forks/letsencrypt,stweil/letsencrypt,bsmr-misc-forks/letsencrypt,jtl999/certbot