PhpUnitWrapper detect generic PHPUnit installs

Call class_exists to trigger an autoload attempt, where composer or other autoloaders can provide a PHPUnit installation.

- PHPUnitWrapper typos fixed
- PHPUnitWrapper_3_5 will now use LSB to get test_name
- Change PHPunit provider from PEAR to composer
- PHPunit is now a composer dev dependency so PEAR can be dropped.