Yadisk

* Fixed argument handling in `upload()`, `download()` and `download_public()`.
Previously, passing `n_retries` and `retry_interval` would raise an exception (`TypeError`).

* Better exceptions (see the docs)
* Added support for `force_async` parameter
* Minor bug fixes

* Fixed yet another `listdir()` bug

* Added `install_requires` argument to `setup.py`

* Return `OperationLinkObject` in some functions

* Fixed `setup.py` to exclude tests