AbstractTest::getDefinition always returns a bound definition

This bugfix causes all tests to always return a "bound" definition - that is all definitions for both suites and tests are bound to scope. This will allow us to do things like this now:

```php
describe("MyThing", function() {
    //we can bind things to a suite at this level now...
    $this->thing = "I am bound to scope";

    it("should do a thing", function() {    

    });
});
```