SSL certificate verify loading server certificate

[JeffRodriguez]

SparkMagic could load server certificate, ca_certs, and use it to verify SSL Server certificate. Instead of relying on a DEFAULT_CA_BUNDLE_PATH. This will require to load the server certificate and validate with requests.
The user case would be in the cases where we can to connect to an SSL intermediary to access livy, and we can't setup a DEFAULT_CA_BUNDLE in a convenient way on the client.
This would be an override configuration.
e.g.
verify_ssl_server_certificate, set to False as default.
If set to True then we would load server certificate to client and set verify to point to the certificate.

[aggFTW]

I think that we could expose a custom_certfiles_path as a configuration and use it with the verify parameter for requests. The default value in python if no path is specified in the config file should be None.

If you are implementing this, please send a PR with unit tests.

[JeffRodriguez]

Thanks Alejandro. I will send the PR ASAP.

[polomarcus]

Hi @JeffRodriguez 😄

I would be interested by the same feature, I can propose a PR if you haven't had the time to work on it

[bhadrip]

Is there any work needed to get this in ? I can work on it, we also need this fix.

There are some comments in this PR - #435 can we reuse it or should i cut a new one ?