API:
- write main test body into tests/isolated/filename.py
- it must write 'pass' to stdout or 'skip:[optional reason]'
- write a test with single line: tests.run_isolated('filename.py')
FIXME: autorun all files in tests/isolated

This deprecates tests.run_python and ProcessBase.
TODO: rewrite old multiline string test bodies to isolated files
TODO: add timeout to p.communicate() in run_python()

If it's determined that a MySQL test should be skipped during setUp(),
but after the parent setUp() has been called, having created and
started a timer, then tearDown() is never called and the timer never
cancelled, but left to expire during some future, unrelated test.

Move call to parent setUp() to end of child setUp() to insure that the
timer is only created and started after it's been determined that the
test shouldn't be skipped (ie create_db()).

https://github.com/eventlet/eventlet/issues/101

- __next__ for iterator interface
- six.next() to get next item
- list(dict.keys())
- popen2.popen4 -> subprocess
- s2b -> b"..." literals
- deprecated assertEquals -> assertEqual
- hub_test test_fork using run_python
- 1L -> 1 long literal
- many PEP-8 fixes

For now, pep8 check is only run for some files known to be clean,
we should clean the rest and enable pep8 check for all files then.

Fixes GH-41 https://github.com/eventlet/eventlet/issues/41