Add a backwards-compatibility import for ServiceTests.

Review Request #7944 — Created Feb. 4, 2016 and submitted — Latest diff uploaded


Review Board


We had a class, ServiceTests, which was a base testcase class for
hosting service unit tests. This was moved recently, which broke
extensions that provided hosting service unit tests based on this.

This restores the import for now. We may want to create something more
formal down the road.

Review Board unit tests pass.

Power Pack unit tests pass.