log.DialogHandler: print formatted record, not just message.

Fixes bug, where DialogHandler would display only %(message) part of
the record, instead of the entire formatted record string.

letsencrypt/log.py

@@ -37,7 +37,7 @@ class DialogHandler(logging.Handler):  # pylint: disable=too-few-public-methods
         lines.
 
         """
-        for line in record.getMessage().splitlines():
+        for line in self.format(record).splitlines():
             # check for lines that would wrap
             cur_out = line
             while len(cur_out) > self.width: