DISPATCH-1304: authservice.py fail at shutdown - improvement
DISPATCH-1304: authservice.py fail at shutdown - improvement

As noted by @astitcher the program was triggering bad behavior in
proton by closing the listener in a signal handler. This commit invokes
a proper shutdown by using flags and closing on a container event.

ChugR/qpid-dispatch,mgoulish/qpid-dispatch,kgiusti/dispatch,apache/dispatch,ErnieAllen/qpid-dispatch,ted-ross/qpid-dispatch,ganeshmurthy/qpid-dispatch,apache/dispatch,mgoulish/qpid-dispatch,kgiusti/dispatch,bhardesty/qpid-dispatch,apache/qpid-dispatch,apache/qpid-dispatch,kgiusti/dispatch,bhardesty/qpid-dispatch,bhardesty/qpid-dispatch,mgoulish/qpid-dispatch,ganeshmurthy/qpid-dispatch,mgoulish/qpid-dispatch,ChugR/qpid-dispatch,bhardesty/qpid-dispatch,ted-ross/qpid-dispatch,ErnieAllen/qpid-dispatch,ted-ross/qpid-dispatch,apache/qpid-dispatch,ChugR/qpid-dispatch,kgiusti/dispatch,ted-ross/qpid-dispatch,apache/dispatch,apache/dispatch,ErnieAllen/qpid-dispatch,bhardesty/qpid-dispatch,kgiusti/dispatch,ErnieAllen/qpid-dispatch,ChugR/qpid-dispatch,ganeshmurthy/qpid-dispatch,ChugR/qpid-dispatch,ted-ross/qpid-dispatch,bhardesty/qpid-dispatch,kgiusti/dispatch,apache/dispatch,apache/dispatch,mgoulish/qpid-dispatch,apache/qpid-dispatch,ChugR/qpid-dispatch,ted-ross/qpid-dispatch,ganeshmurthy/qpid-dispatch,ErnieAllen/qpid-dispatch,ganeshmurthy/qpid-dispatch,bhardesty/qpid-dispatch,mgoulish/qpid-dispatch,apache/dispatch,ganeshmurthy/qpid-dispatch,apache/qpid-dispatch,apache/qpid-dispatch,ErnieAllen/qpid-dispatch