Implement logging control in qpid::messaging API

Currently there is one major omission from the qpid::messaging API: That is control of the internal logging used by qpid itself. This was present in the qpid::client API albeit not really supported or documented.

This breaks down to 2 essential pieces and one optional one:

• Allow library client code control of the logging levels etc which are logged.
• Allow clients to handle logging output in a way that suits the application
• (Optional) Allow clients to inject logged messages into the logging stream