Feature - PHPUnit hardening

This PR simply sets more strict defaults to the `phpunit.xml` file to make PR merging more safe. I've also renamed the `phpunit.xml` file to `phpunit.xml.dist` since its a default distributed configuration (that's the new standard practice).

This gives us the ability to have stricter tests, more confident merges, and have some niceties like colored test output.

:+1: 

**EDIT**: No longer a work in progress.