EJB Attachment protocol mismatch

In both EJB client and server code, on method invocations where context data is sent, the sender writes the attachment count as a packed integer but the reader consumes it as an unsigned byte. This is not good.

The fix:

• In protocol 3 and higher, always read and write a packed integer
• In protocol 2 and lower, always read a packed integer but write a signed byte, failing if more than 127 attachments are present

Note that this is only temporary in the WFLY project as the server code should ultimately be moving to live in the ejb-client library.