title: Change log level in unittest
body: <p>I have the impression (but do not find the documentation for it) that unittest sets the logging level to <code>WARNING</code> <em>for all loggers</em>. I would like to:</p>
  
  <ul>
  <li>be able to specify the logging level for all loggers, from the command line (when running the tests) or from the test module itself</li>
  <li>avoid unittest messing around with the application logging level: when running the tests I want to have the same logging output (same levels) as when running the application</li>
  </ul>
  
  <p>How can I achieve this?</p>