Removing specs from finagle/finagle-native test.

Going along with the corresponding issue https://github.com/twitter/finagle/issues/290 and my other PR on the subject https://github.com/twitter/finagle/pull/292


Haha, I literally told him the opposite.  I like having a Context class because it makes it clear that you're not sharing any mutable state.  Why do you think it would cause a test failure?