Handle unicode errors as well

Fixes rb#434
Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/trans/util.py

@@ -226,7 +226,7 @@ def report_error(error, exc_info, request=None, extra_data=None):
     LOGGER.error(
         'Handled exception %s: %s',
         error.__class__.__name__,
-        str(error)
+        unicode(error).encode('utf-8')
     )
 
     # Print error when running testsuite