Error handling in base_client.py causes AttributeError

[mkresse]

Error handling seems to be broken, as a ReadTimeout triggered by a request to orlo causes an AttributeError, because a nonexistant attribute "message" is logged:

Traceback (most recent call last):
  File "/usr/local/lib/python3.7/dist-packages/orloclient/base_client.py", line 39, in _get
    **req_kw_args
  File "/usr/local/lib/python3.7/dist-packages/requests/api.py", line 75, in get
    return request('get', url, params=params, **kwargs)
  File "/usr/local/lib/python3.7/dist-packages/requests/api.py", line 60, in request
    return session.request(method=method, url=url, **kwargs)
  File "/usr/local/lib/python3.7/dist-packages/requests/sessions.py", line 533, in request
    resp = self.send(prep, **send_kwargs)
  File "/usr/local/lib/python3.7/dist-packages/requests/sessions.py", line 646, in send
    r = adapter.send(request, **kwargs)
  File "/usr/local/lib/python3.7/dist-packages/requests/adapters.py", line 529, in send
    raise ReadTimeout(e, request=request)
requests.exceptions.ReadTimeout: HTTPSConnectionPool(host='orlo.es.ecg.tools', port=443): Read timed out. (read timeout=10)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  ...
  File "/usr/local/lib/python3.7/dist-packages/orloclient/objects.py", line 57, in __getattr__
    self.fetch()
  File "/usr/local/lib/python3.7/dist-packages/orloclient/objects.py", line 101, in fetch
    self._data = self.client.get_release_json(self.release_id)
  File "/usr/local/lib/python3.7/dist-packages/orloclient/client.py", line 138, in get_release_json
    response = self._get(url)
  File "/usr/local/lib/python3.7/dist-packages/orloclient/base_client.py", line 51, in _get
    logger.debug(e.message)
AttributeError: 'ReadTimeout' object has no attribute 'message'