Ouput Buffering Fixes

Closes #1545 #1553 

Was a bit unsure about removing this bit:

```php
while (!defined('PHPUNIT_TESTSUITE') && ob_get_level() > 0) {
    ob_end_clean();
}
```

But it seemed to be added arbitrarily? There's no need to reduce the output buffering to zero as long as the test keeps track of the output buffering level it started.