jt400: program call should support binary format

Data queue message exchange supports both text and binary formats and so should the remote program call exchange. The specification is the same as the one for the data queue.

Additionally, this patch supports the concept of ommiting a parameter. This is achieved by passing null as the parameter value.

Implementation note:
Since I don't know Camel's policy regarding API breaking, I opted to refer to Jt400DataQueueEndpoint.Format; but Format should now be a top-level class, since the concept is the same for data queues and programs.