firstly, test_cipher_on_target() will try at least 4 connections before
incurring the sleep, for aggressive rate limiter on server side it may be
too much, so sleep before every connection
secondly, because running external commands like sleep incurs a fork
penalty, we first check if it is necessary
scan all the machines from top-1m.csv file, wait for completion
of all jobs
i=1 is an off-by-one-error
support top-1m.csv files with arbitrary number of sites
run scans for many hosts at a time, but don't run more than
specified amount
in case where default domain name doesn't resolve or doesn't have
port 443 open, retry with www. prefix
