* Test sanity cleanups

Partially addresses #87

- Remove manual lists of tests in favor of loadTestsFromName. This
  mostly gets all test runners running the same number of tests.
- Remove `additional_tests`, which was just duplicating the discovered
  tests. No modern test runner seems to need it.
- Change the two compatibility skip decorators to actually use
  unitetest skips, which helps with the reporting.

* Per @tseaver, drop most test_suite functions.

* Port remaining doctest to unittest.

* Make the odd tests work on all supported python versions

Since we no longer support 3.2 we can use the literal syntax.

This was done with a quick sed script.

 '__code__', '__defaults__', '__func__', and '__self__' all work fine on
Python 2.6+.

We *can't* test the classAdvice stuff under Py3k.  Need to deprecate it
before the 4.0 release.