Extracted retry logic from request.
Added handling of confirmable messages in the server.
Refactorings in the CON Server support
Added CON support to request.
Little docs adjustements.
Added ACK to CON responses in request.
Removed spurious test failures.
Correct handling of Empty messages.
Two more examples.
Specifying the default of `confirmable` in request.
Merge pull request #1 from mcollina/confirmable

Confirmable Messages Support