Set lowest log level by default.

As we can only increase verbosity with commandline flags, we
should set the least verbose log level by default.

diceware/logger.py

@@ -57,7 +57,7 @@ def configure(verbosity=None):
     """
     if verbosity is None:
         return
-    logger.setLevel(logging.INFO)
+    logger.setLevel(logging.CRITICAL)
     if verbosity > 1:
         logger.setLevel(logging.DEBUG)
     logger.addHandler(logging.StreamHandler())

tests/test_logger.py

@@ -22,8 +22,8 @@ def test_configure():
     # we can configure the logger.
     my_logger = logging.getLogger("ulif.diceware")
     configure(None)
-    assert my_logger.level == 0
+    assert my_logger.level == logging.NOTSET
     configure(0)
-    assert my_logger.level == logging.INFO
+    assert my_logger.level == logging.CRITICAL
     configure(2)
     assert my_logger.level == logging.DEBUG