IDE support

I created an [Android Studo plugin](https://github.com/evant/android-studio-unit-test-plugin) which requires a gradle plugin to provide a model for the ide to read. I don't expect you to merge this pull request as-is because it dependes on a local library that provides the interface between the plugin and the ide. This [library](https://github.com/evant/android-studio-unit-test-plugin/tree/master/android-unit-test-model) needs to be hosted seperatly on maven central so that the gradle plugin can be updated independently. I'm not sure if you want to pull this in and maintain it yourself, or have me do it.
There is nothing special I do to configure the JUnit configuration in this regard. The only changes my plugin makes is to add the Robolectric System properties. All I know is that it wasn't working before I added this task, and does work afterwords. My only guess is it's hardcoded for gradle projects since the java plugin adds the same task.