Restructured Logger with nice clean interface.

Breaking changes: Logger no longer supports info/error/warning console() replaced with report_text()

trains/backend_api/session/callresult.py

@@ -81,7 +81,7 @@ class CallResult(object):
                 # response.validate()
         except Exception as e:
             if logger:
-                logger.warn('Failed parsing response: %s' % str(e))
+                logger.warning('Failed parsing response: %s' % str(e))
         return cls(meta=meta, response=response, response_data=response_data, request_cls=request_cls, session=session)
 
     def ok(self):

trains/backend_api/session/session.py

@@ -215,7 +215,7 @@ class Session(TokenManager):
                 res.status_code == requests.codes.service_unavailable
                 and self.config.get("api.http.wait_on_maintenance_forever", True)
             ):
-                self._logger.warn(
+                self._logger.warning(
                     "Service unavailable: {} is undergoing maintenance, retrying...".format(
                         host
                     )