Travis: Slack.com integration
tpool: Windows compatibility, fix ResourceWarning. Thanks to Victor Stinner

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
Fix timers not cleaned up on MySQL test skips

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()).
db_pool.BaseConnectionPool.clear updates .current_size #139
tests: db_pool: test .clear() updates .current_size GH-139
Fix monkey_patch() on Python 3

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