Catch keyboard interrupt and sigterm in broker process and properly shut down ZMQ
Remove unused code path; return default value of option does not exist (#3937)
Make state_sql_uri and zmq_poller_timeout configurable; remove unused code path in init_db()
Merge branch 'master' of github.com:kolab-groupware/bonnie

Conflicts:
	bonnie/broker/brokers/zmq_broker/__init__.py