HORNETQ-1429 Adding cool Proton-cpp example

https://issues.jboss.org/browse/HORNETQ-1429

This includes small fixes on Proton examples and also
adding a brand new C++ example using qpid cpp client

You will also see a few other tweaks around ProtonHandling on this commit
that were left by accident on prevoius commits.
Merge pull request #1919 from clebertsuconic/master

HORNETQ-1429 Adding cool Proton-cpp example