Add SimpleTest support

This perhaps isn't the prettiest implementation possible, but this commit incorporates an updated version of the patch suggested here:

http://demo.codesetter.com/phpundercontrol-drupal-6-n-7

To configure it, write a test harness that uses the `XmlReporter` class; something along the lines of:
```
<?php
// Includes...
$reporter = new XmlReporter;
$harness = new TestSuite;
$harness->run($reporter);
```

Now edit CruiseControl's `config.xml` so that the `test-result.xml` file gets merged into the resulting build log. We need to do this so that the log can be parsed to generate the SimpleTest page for each build:
```
<log>
    <merge file="projects/${project.name}" />
</log>
```

Finally, add a target to your `build.xml`, and call it from the the target CruiseControl is calling:
```
<target name="test" description="Run the test suite">
    <exec executable="php" dir="${basedir}" output="${basedir}/build/logs/test-results.xml">
        <arg value="path/to/harness.php" />
    </exec>
</target>
```

I need to work on displaying failed tests, though I'm not particularly knowledgeable about XSLT, so this may take me a few days. For a quick overview, this code should work fine, however.