PROTON-176: Add unit tests for qpid::proton::Messenger in Perl.

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1435339 13f79535-47bb-0310-9956-ffa450edef68
PROTON-176: Fixes to qpid::proton::Messenger found by unit tests.

These fixes address issues discovered while writing the unit tests for
the Messenger class.

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1435340 13f79535-47bb-0310-9956-ffa450edef68