Remove web test runner, and only use phpunit.

This set of changes implements the ideas in #12. I have mixed feelings about removing the `test.php` file.

In the :+1: side for keeping `test.php`

* It is easier for CLI newbies to get testing working.
* It has a nice coverage view per file.

On the :-1: side of keeping `test.php`:

* It is a snowflake. Both in CakePHP and in PHP in general. No other frameworks maintain their own web runner for PHPUnit. I'm considering either contributing to/forking VisualPHPUnit so we can provide a more general use test runner.
* CakePHP has a non-trivial amount of code dedicated to supporting the web-runner. I'd like to see that go away.

I think most CLI newbies are also people who use full featured IDE's. Most good IDE's have a way of integrating with PHPUnit. IDE integration might be more valuable/useful to this group. It certainly is less work once you get it working.