grails-testing-support: re-enable views-json plugin and add dependsOn

[jamesfredley]

compileTestGroovy.dependsOn(compileGsonViews) added to resolve

Reason: Task ':examples-demo33:compileTestGroovy' uses this output of task ':examples-demo33:compileGsonViews' without declaring an explicit or implicit dependency. This can lead to incorrect results being produced, depending on what order the tasks are executed.
    
    Possible solutions:
      1. Declare task ':examples-demo33:compileGsonViews' as an input of ':examples-demo33:compileTestGroovy'.
      2. Declare an explicit dependency on ':examples-demo33:compileGsonViews' from ':examples-demo33:compileTestGroovy' using Task#dependsOn.
      3. Declare an explicit dependency on ':examples-demo33:compileGsonViews' from ':examples-demo33:compileTestGroovy' using Task#mustRunAfter.