fixes #22

I wasn't able to run the tests after making this change because of the following error which I was unable to resolve:

````
dmurtagh@Donals-MacBook-Air:~/workspace/examples/grails-fields$ grails test-app --stacktrace
| Environment set to test.....
| Error Error executing script TestApp: No such property: projectTestRunner for class: TestApp (NOTE: Stack trace has been filtered. Use --verbose to see entire trace.)
groovy.lang.MissingPropertyException: No such property: projectTestRunner for class: TestApp
	at TestApp.run(TestApp:27)
	at TestApp$run.call(Unknown Source)
	at gant.Gant.prepareTargets(Gant.groovy:607)
````