Vt-py

* Add error handling to 'download_file' (64)

* Add a timeout parameter to the `Client` object (https://github.com/VirusTotal/vt-py/pull/54)
* Fix truncated responses under high load error (https://github.com/VirusTotal/vt-py/pull/56)
* General code improvements (https://github.com/VirusTotal/vt-py/pull/59, https://github.com/VirusTotal/vt-py/pull/60)

* Fix bug that returned None value between batches when iterating over a collection (50)

- Add script to create references.
- Add `relationships` in the Object's `to_dict` method.
- Adding proxy support via aiohttp.ClientSession trust_env (39)
- Fix for interator class when limit=0 (38)

- Add File Behaviour feed compatibility
- New examples of usage
- Removing pytest requirement

WSGI applications developed with Python web frameworks (like Django or Tornado) create threads under the main process for handling user requests and Async IO is unable to generate an event loop for those threads if it is not yet created. We are now doing this on our end for adding compatibility with WSGI apps struggling with this problem.