Camel-8024 Improvement to camel-sjms JMSMessageHelper

Hi all,

This PR is related to: https://issues.apache.org/jira/browse/CAMEL-8024

Please let me know if something can be improved or if something is wrong. I've added some check on discoverMessageTypeFromPayload method and a new test class.

Bye,
Andrea
This test doesn't test the type of JMS Message produced.. You should be asserting that a BytesMessage was produced. And that the contents of the Exchange.getIn().getBody() is a byte[].