PROTON-1282: Seg Fault in Ruby Messenger pn_messenger_free
PROTON-1282: Seg Fault in Ruby Messenger pn_messenger_free

Add an at_exit to ensure the Messenger is stopped before shutdown.

kgiusti/qpid-proton,alanconway/qpid-proton,astitcher/qpid-proton,ssorj/qpid-proton,alanconway/qpid-proton,ChugR/qpid-proton,ChugR/qpid-proton,kgiusti/qpid-proton,alanconway/qpid-proton,ssorj/qpid-proton,astitcher/qpid-proton,apache/qpid-proton,alanconway/qpid-proton,ChugR/qpid-proton,gemmellr/qpid-proton-j,ChugR/qpid-proton,gemmellr/qpid-proton,alanconway/qpid-proton,ChugR/qpid-proton,alanconway/qpid-proton,apache/qpid-proton,apache/qpid-proton,astitcher/qpid-proton,astitcher/qpid-proton,kgiusti/qpid-proton,ssorj/qpid-proton,kgiusti/qpid-proton,kgiusti/qpid-proton,gemmellr/qpid-proton,gemmellr/qpid-proton-j,gemmellr/qpid-proton,apache/qpid-proton,apache/qpid-proton,gemmellr/qpid-proton,ssorj/qpid-proton,kgiusti/qpid-proton,gemmellr/qpid-proton,astitcher/qpid-proton,apache/qpid-proton,ssorj/qpid-proton,ChugR/qpid-proton,ssorj/qpid-proton,gemmellr/qpid-proton,astitcher/qpid-proton