Stomp.py

* Fix logging simplification code (should not be logging to root appender - https://github.com/jasonrbriggs/stomp.py/issues/275)

* Fix for credentials exposure (https://github.com/jasonrbriggs/stomp.py/pull/244)
* Check for ``STOMP_SKIP_HOSTNAME_SCAN`` environment variable before extending ``LOCALHOST_NAMES``
* Remove python2 backwards compatibility
* Update dockerfile for better local testing
* Fix docker and travis setup, so there are consistent builds both locally and via CI
* Drop deprecated start/stop methods from connection (issue https://github.com/jasonrbriggs/stomp.py/issues/257)
* Fix for missing return in get_ssl (https://github.com/jasonrbriggs/stomp.py/pull/258)
* Clear heartbeat event after heartbeat loop ends (https://github.com/jasonrbriggs/stomp.py/pull/260)
* Update listener to move receive/message_received/heartbeat_received vars inside the 'with' blocks (https://github.com/jasonrbriggs/stomp.py/pull/252)
* Simplify logging calls
* Tidy up listeners (correct the behaviour of TestListener)
* Fix problem with double-disconnect notification (ihttps://github.com/jasonrbriggs/stomp.py/issues/245)
* Add facility for PrintingListener to write to log rather than print statements

* Infinite retry attempts (https://github.com/jasonrbriggs/stomp.py/pull/235)
* Terminate heartbeat thread on shutdown (https://github.com/jasonrbriggs/stomp.py/pull/234)
* Remove unused wait_on_receipt parameter (https://github.com/jasonrbriggs/stomp.py/pull/237)
* Reduce verbosity in logging to not include headers unless debug level is turned on (potential security issue as per: https://github.com/jasonrbriggs/stomp.py/issues/226)
* Fix for disconnect receipt usage in transport (https://github.com/jasonrbriggs/stomp.py/issues/212)
* Add __enter__/__exit__ to Connection so it can be used as a context (https://github.com/jasonrbriggs/stomp.py/issues/215)
* Additional ssl options (https://github.com/jasonrbriggs/stomp.py/pull/221/)

* Fix for deadlock issue (https://github.com/jasonrbriggs/stomp.py/issues/197)
* Fix for encoding issue (https://github.com/jasonrbriggs/stomp.py/issues/195)
* Fix for reconnect issue (https://github.com/jasonrbriggs/stomp.py/issues/202)

* Tidy up API (remove need for start/stop methods on the connection)
* Make updating listeners thread-safe (https://github.com/jasonrbriggs/stomp.py/pull/174)
* Merge patch from Scott W for configuring grace period for heartbeat timeouts (https://github.com/jasonrbriggs/stomp.py/pull/180)
* Fix ack/nack in CLI
* Add missing on_receiver_loop_completed handler to ConnectionListener

* Replace custom script with setuptools' entry_point for creating the executable
* Stop waiting for protocol answers when the connection has been closed
* Add check for is_connected on transport.stop
* Change command-line tool to use docopt