PHPUnit integration by default in Codeigniter Framework;

PHPUnit integration by default in Codeigniter Framework (via Composer or not). 

- The default folder is "application/tests";

- The error CLI views was based in @narfbg recomendations in issue  https://github.com/EllisLab/CodeIgniter/pull/2279;

- Default example created (file "application/tests/WelcomeTest.php");