Update C++ code examples for Proton 0.14.0

[scholzj]

It looks like our code examples are not compatible with Proton 0.14.0 (https://travis-ci.org/Eurex-Clearing-Messaging-Interfaces/C-Code-Examples/builds/152728113). They should be updated.

[tomas-soltys]

Examples are working with qpid-proton 0.14.0 as well as with 0.13.1, but travis and circle ci are both using Ubuntu 14.04 where c++ compiler does not fully support C++ 11 which is required by C++ binding in proton 0.14.0