Phpunit tests completion

Hey,
As I mentioned in #159 , I've done some fixes and corrections for PHPUnit test environment for Magallanes. I've also noticed and fixed following problems:
* lack of `phpunit` in `bin` directory while doing installing dependencies by composer. I've fixed that by adding `bin-dir` to `composer.json`
* no colors... for phpunit output :) Changed phpunit default configuration in `phpunit.xml.dist`
* coverage - I've added `coversDefaultClass` and `covers` in test class to be sure that those test methods test that what we want to test

Please free to code-review!
@SenseException @andres-montanez