Merge branch 'rr/send-email-ssl-verify'

Newer Net::SMTP::SSL module does not want the user programs to use
the default behaviour to let server certificate go without
verification, so by default enable the verification with a
mechanism to turn it off if needed.

* rr/send-email-ssl-verify:
  send-email: be explicit with SSL certificate verification

diff --cc Documentation/config.txt
Simple merge

diff --cc git-send-email.perl
Simple merge