Use API function getOutput() in UnishTestCase instead of private class variable
Update /tests/README.md for --configuration in test running
Update OutputFormatUnitCase for pretty printed JSON under PHP 5.4
self::sites is new static variable in test cases.

Get to it with a new $this->getSites() method.

This enabled me to refactor configTest to use separate test methods without having to reinstall Drupal for every one. Other tests will get similar mimprovement soon.