Improve the default logging configuration

Using the suggested logging configuration, messages were being lost
including serious exceptions, due to the 'django' logger not being
defined.

This brings local_settings.py in line with the upstream changes to
resolve this, and also adds a formatter to make the log message format
more consistent with other projects.

Change-Id: I13ea88602575196681e2ed6f0e5cea2cca8fddd6
Related-Bug: #1236423
Set LOGOUT_URL properly in horizon settings

LOGOUT_URL depends on the root_path just like LOGIN_URL was is already set in
the template.

Without this change, a user whose session timeouts was redirected to
/auth/logout (404 error) instead of /horizon/auth/logout.

Change-Id: I4f7c7ab4d20eed514c48d79d78980d7415d70be5
Merge "Set LOGOUT_URL properly in horizon settings"