Django now *requires* the `SECRET_KEY` conf var in the settings file
Add coverage, rednose & -sv to the nosetests call
Change how truck decide to disable or not signals

The `LISTENERS_OFF_BY_DEFAULT` variable is now a lazy accessor of the
`settings.TESTING` var. It's smart enough to detect when it should
disable the signals or not given the `TESTING` variable value;

If it is empty, does not exist or contain "acceptance", the flag is
False, the signals won't be disabled, otherwise the flag is set to true
and the signals will be disabled.
Remove custom `get_packages` impl from the setup.py script
New release: 0.1.4