New option (--not-valid-longer-than) to check if a certificate is val…

…id longer than the specified number of daysXSXC

Fixed the tests and prepared the next version

Fixes matteocorti#185

Better error message in case of connection refused

Better error message in case of an invalid host

Updated the usage

SMTP connections with -name only with OpenSSL versions supporting it

Fixed matteocorti#184

Prepared the new version

Option to specify the dig binary and fix in the command line validati…

…on checks