Added suport for configuring SSL connections. This done by adding two ad...

Hi,
I have been using your gem to connect to an XMLRPC service. However, that server requires client certificates. EM::HttpRequest has the right hooks, but it wasn't exposed through your API. I added some code in the feature branch 'SSL' to do that in a transparent fashion between EM and non-EM use.

    client = XMLRPC::Client.new2(url)
    client.ssl_options = {
        private_key_file: '/Users/max/.gcf/max-geni.key.cert',
        cert_chain_file: '/Users/max/.gcf/max-geni.key.cert',
        verify_peer: false,

        # only for non-EM mode
        ca_file: '/Users/max/.gcf/trusted_roots/GPO.crt' 
    }

Sorry, no tests as didn't really know how to do this effectively without a server to test against.

Cheers,
-max