Sportmonks

* Add `SoccerApiV2.aggregated_top_scorers()` method. This method returns top scorers for aggregated over all stages of a season. The `SoccerApiV2.top_scorers()` method returns top scorers broken down by each stage of the season which is inconvenient if you don't care about the season's stages.

* Fix [bug](https://github.com/Dmitrii-I/sportmonks/issues/9) where `tzlocal` was missing in the `install_requires` of `setup.py`. As a result you could install `sportmonks` but not run it. The bug did not resurface during tests because `tzlocal` was actually specified in the `requirements-tests.txt`.

* Fix [bug](https://github.com/Dmitrii-I/sportmonks/issues/8) in which the package was unusable on Windows because the URLs were constructed using path separator which on Windows is a backslash not a slash. This has been fixed by using `urllib.parse.urljoin` function.

* Add parameter `includes` to `SoccerApiV2.player` method.

* Stop caching methods. As such caching has been removed from `SoccerApiV2.bookmaker`, `SoccerApiV2.continent`, `SoccerApiV2.country`, `SoccerApiV2.league`. Caching can still be done by callers with the `functools.lru_cache` decorator.
* Fix bug in `SoccerApiV2.fixtures` and `SoccerApiV2.fixtures_today`. When parameter `league_ids` was specified and the resulting response contained more than 100 fixtures, then the fixtures beyond the first 100 contained also fixtures not belonging to the specified `league_ids`.
* Parameter `include` has been renamed to `includes`. This name is better because it can contain zero or more includes, not zero or one.
* Accept any iterable in the `includes` parameter, not just tuples. Lists, sets, and other iterables with a `__getitem__` magic method will work. Strings, even though iterables, are converted to a one-element list. This allows also to pass single include lazily as `includes='continent'`, instead of `includes=['continent']`. In fact this could also be considered as a bug fix, because in previous versions the strings were accepted too, but were passed as single character includes and SportMonks API was not raising any error.
* Remove API token from logs for better security. Note, that the API token will still appear unedited in logs of `requests` and `urllib3` packages.
* The API client attributes `base_params` and `base_headers` are now private (i.e. renamed to `_base_params` and `_base_headers`.

* Fix bug in `SoccerApiV2.season_results()` default value. Default value must an empty tuple not `None`.
* Stop caching `SoccerApiV2.season()` method. When `season()` was called and the cache was empty, a call to `seasons()` was made to populate the cache. This proved to be too slow to be useful.