refactor: set cplex logger name (#162)

cplex_interface.Configuration was setting the root logger level to CRITICAL which silences most other logging output across the process.

optlang/cplex_interface.py

@@ -470,7 +470,7 @@ class ResultsStreamHandler(StreamHandler):
             def flush(self):
                 self.logger.debug(self.getvalue())
 
-        logger = logging.getLogger()
+        logger = logging.getLogger('cplex.problem')
         logger.setLevel(logging.CRITICAL)
         error_stream_handler = ErrorStreamHandler(logger)
         warning_stream_handler = WarningStreamHandler(logger)