Add middleware_ssl_* parameters

The modules mixes middleware ssl and mcollective ssl. 

The middleware ssl (plugin.activemq.pool.1.ssl.{ca,cert,key}) is used for connection encryption. The nodes puppet key/cert can be used.

The mcollective ssl (plugin.ssl_server_{public,private}) is a shared secret among all mcollectiv servers. The nodes puppet key/cert can't be used. The ca.pem isn't used at all for securityprovider=ssl.

The patch moves the key/cert files from /etc/mcollective to /etc/mcollective/ssl/{middleware_key,middleware_cert,middleware_ca,server_public,server_private}.pem and introduces "middleware_ssl_ca" (default: ssl_server_ca) , "middleware_ssl_key" and "middleware_ssl_cert".