New formula: cmockery2 1.3.8

Not really seeing a good way to make a test for this.  ```cmake.rb``` does have a decent one, but it's an executable which can be provided command line argument to run.  cmockery2 isn't really like that.  cmockery, and cmocka don't have tests in their formula either, so no concepts there I can copy from.

Thoughts? :smile: