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.
Yes, this is for creating junit run configurations. 

I guess it just ignores it if it doesn't exist? I just noticed that the test classes weren't being built before running until I added this task. I noticed it showing up in the info bar at the bottom of the ide when I ran a test and added it on a hunch.