Output of dry run improved

The Output of dry run was insufficient because it only listet the "array_keys" which have been just numbers. In the unfortunate case, that only one message was added this resultet in an output like : "Added Messages: 0". Therefore are now the real number of messages shown and with verbose option even the message IDs with initial "desc" translation.

Comment on composer.json:
As I wanted to test my code I came across the issue that an old version of di-extra-bundle (1.0.1) was loaded. This version has no dependency on aop which caused exceptions, due to the fact that the AOPBundle is loaded in the FunctionalTest AppKernel.php