Uses the namespaced PHPUnit\Framework\TestCase class instead of the global PHPUnit_Framework_TestCase class as able (forward compatibility to PHPUnit 5.4.3 which also has the compatibility layer and inherently PHPUnit 6 where the namespaced classes are actually used)
Moves a couple of files out of directories that really don't need to be there (only reason before was because of the autoloader)
Removes the abandoned changelog for the tests directory
The composer update phpunit/phpunit command was run with Composer 1.4, hence the changes in its class loader