Elastic-apm

* fixed an issue when logging messages that are not strings (295, 312)
* backported some documentation fixes

* fixed an issue with detecting names of wrapped functions that are partials (294)
* fixed a bug in Flask instrumentation that could appear together with FlaskAPI (286)

* added sanitization for `Set-Cookie` response headers (264)
* added instrumentation for the non-standard `Connection.execute()` method for SQLite3 (271)
* added "authorization" to list of sensitive keywords, to ensure that "Authorization"
HTTP headers are properly sanitized (275)
* taught the Logbook handler how to handle the `stack=False` option (278)
* fixed a race condition with managing the timer-send thread (279)

- adapted "black" code formatter for this repository (262)
- **BREAKING**: dropped support for Python 3.3 (242)
- **BREAKING**: changed order of precedence when evaluating configuration (255, 261)
- **BREAKING**: changed default value of `span_frames_min_duration` setting
from `-1` (always collect) to `5` (only collect for spans longer than 5 ms) (243)
- added instrumentation for pymssql (241)
- added instrumentation for pyodbc (238)

- fixed an issue with Django Channels (232, 233)

- introduced consistent logger name scheme for all elasticapm internal log messages (212)
- added instrumentation of cassandra-driver (205)
- added instrumentation of elasticsearch-py (191)
- added Flask 1.0 to the test matrix (207)
- fixed an issue with our minimalistic SQL parser and "fully qualified" table names (206)
- fixed issue with spans in Django’s `StreamingHTTPResponse` not being captured (201, 202)
- fixed issue with spans with Flask’s streaming response not being captured (201, 202)

**NOTE**: This will be the last release with support for Python 3.3.