Hardening build rules

Now that [this issue](https://code.google.com/p/google-api-java-client/issues/detail?id=867) is resolved, the build is passing. I've had to update a couple of other bits to get PowerMock to run correctly, as well as bumping the versions to current.

PTAL @broady @domesticmouse 
The ~/.gradle/gradle.properties is used only when uploading to maven central, so these empty params are provided only to allow build.gradle to pass compilation checks.