Simplify timing implementation.
Remove support for the X-Forwarded-For header.

Follow the tracks of Django where it was removed in version 1.1. The
reasons and a workaround are described here:
https://docs.djangoproject.com/en/dev/releases/1.1/#removed-setremoteaddrfromforwardedfor-middleware

Fix #338.
Take advantage of TestCase.settings.

It's available in Django >= 1.4.
Support DEFAULT_CHARSET != 'utf-8'. Fix #15.
Support non-ASCII queries in the SQL panel.

Fix #28.
Support non-ASCII SECRET_KEY settings.

Ref #28.
Add a screenshot to the README.

Fix #182. Thanks Miserlou for the idea.
Test that non-ASCII data in sessions works.

Fix #67.
#151 -- Logging panel fails on invalid string representations
Merge pull request #415 from Bouke/tickets/151

Fix #151 -- Logging panel fails on invalid string representations
Small test refactoring.
Ensure the toolbar only outputs valid XML.

This allows using it in websites served with the application/xml+xhtml
mime type. Fix #221.