Add ignore-ssl and ca-certs options to CLI

Fixes #54

Both options are set either in the config file or as runtime
arguments.

ignore-ssl option allows connections without checking SSL
certificates

The ca-certs option provides a CA file for SSL authentication

These options are mutually exclussive

The default behavior is to raise SSL errors if no cert files are
provided

In case of an SSL error, kamaki stops and notifies the user
except if they use the ignore-ssl option