SSL Certificate Validation

-checks if the certificate is expired or not
-warning can occur based on user settings
Looks like you have no way to do that with `ssl`, by default if it cannot verify the path, it will just fail https://github.com/pypa/ssl/blob/master/ssl/_ssl2.c#L327-L330
Not sure about this one, maybe other softwares dealing with X509 like openssl do have an extensive list of paths hardcoded. Dunno actually ... @remh any opinion?