Rewrite of Hypertest

This pull request contains "hyperunit.py", a rewrite of "hypertest" to use simple Python unit tests instead of the JSON-based tests previously used with "hypertest."  Hyperunit.py also introduces a REPL and temporary Hyperdex configurations for testing purposes.

It has not been patched into automake; more work is needed there to make sure it picks up the right PYTHONPATH and PATH, and I lack the proficiency with autotools to sort out the necessary steps there.

I have also backported all of the legacy unit tests and cleaned them up.