Fix for PROTON-331, this includes the following changes:
 - factored duplicate frame writing code into common FrameWriter class
 - fixed max frame size negotiation
 - added accessors for remote max frame size
 - simplified buffer management inside TransportImpl
 - fixed processing of the transport work queue
 - fixed session flow control
 - added per session tracking and accessors for incoming/outgoing bytes
 - added configuration for session capacity
 - fixed Binary.toString()
 - added get/setContext to java Connection
 - added useful messages to the java shim's unsupported operation exceptions
 - fixed an error in the C engines computation of outgoing bytes
 - added some test assertions


git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1509238 13f79535-47bb-0310-9956-ffa450edef68