debug level logs should not be translated

According to the OpenStack translation policy available at
https://wiki.openstack.org/wiki/LoggingStandards debug messages
should not be translated. Like mentioned in several changes in
Nova by garyk this is to help prioritize log translation.

This patch adds a new hacking check - N319 - that ensures all
debug log messages don't have translations.

Change-Id: Id9c2715f25c8f2ea52235aba4bd1583655391584
Implements: blueprint debug-translation-removal
Closes-Bug: #1318713
Merge "debug level logs should not be translated"