Dependency on PRC for tests

[d-w-moore]

First, this change will introduce a dependency on PRC, which is currently unprecedented. Personally, I don't think we want that.

HOWEVER, I have learned very recently that no mechanism currently exists which will trigger the atomic API PEPs. So seeing as how this is the only way to do this in existence, I think we can let it pass for now.

We need to do one of two things:

1. The test hook needs to install PRC in order for the tests to run
2. We add a unittest.skip decorator to this test with a note about how it can only run on systems with PRC available and is only being run manually at this time?

Let's make an issue for when the magical new imeta option appears :)

Originally posted by @alanking in #95 (comment)