Ignore permission denied and not found errors in the middleware logger.

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/apps/common/middleware/error_logging.py

@@ -2,11 +2,16 @@ from __future__ import unicode_literals
 
 import logging
 
+from django.core.exceptions import PermissionDenied
+from django.http import Http404
+
 logger = logging.getLogger(__name__)
 
 
 class ErrorLoggingMiddleware(object):
     def process_exception(self, request, exception):
+        if not isinstance(exception, (PermissionDenied, Http404)):
+            # Don't log non critical exceptions
             logger.exception(
                 'Exception caught by request middleware; %s, %s', request,
                 exception