Update tests to run from a Gradle script

[bryantrobbins]

Gradle is a build tool (like Ant, Maven) written in Groovy. It has a plugin for node (https://github.com/srs/gradle-node-plugin) and may be able to run Karma tests as well (http://stackoverflow.com/questions/22336537/how-to-run-js-karma-tests-from-gradle). Of course, it supports JUnit tests and the Maven project structure out of the box as well.

Since we have such a mix of languages, maybe we could look into a language-neutral build/test/deploy approach down the road.