RabbitMQ client support for SSL without client certificate or tls version

The initial implementation of ssl in rabbitMQ was done in 2.4 patch 42. It requires 3 separate properties, and if any are null, ssl is not set up:

grouper.messaging.system.rabbitmqSystem.tlsVersion = TLSv1.1

grouper.messaging.system.rabbitmqSystem.pathToTrustStore = ...

grouper.messaging.system.rabbitmqSystem.trustPassphrase = ...

 The client certificate shouldn't be strictly necessary. Also, the RabbitMQ client api even has a method to use ssl without even needing the version. Proposed:

grouper.messaging.system.rabbitmqSystem.tlsVersion = default

The default would be implemented the way amqp-client ConnectionFactory implements the default, which is 1.2 if it's available, otherwise 1.1. The trust store would be optional, and only used if set.