Closes #178

Some tests will induce behavior that causes the remote end to close
the connection before all of the data has been written.  With small
kernel buffer sizes, this can cause an EPIPE error.  Since the test
expects an early close, this can be ignored.

The importlib module must use real thread locks, not eventlet.Semaphore.

The os.open() function got a new option keyword-only dir_fd parameter in
Python 3.3:
https://docs.python.org/3/library/os.html#os.open

With this change, the open() now accepts the dir_fd parameter.

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/pull/167
Signal socket bind to 127.0.0.1, '' does not work on Windows
sock.close() to fix ResourceWarning with python3 -Wd

Some error paths concatenate the output of "type" with a string,
which gives TypeError: cannot concatenate 'str' and 'type' objects,
rather than describing the actual error.

Closes #149 GH
Closes #150 GH

Conflicts:
	eventlet/hubs/twistedr.py