Fix leak of os.pipe() file descriptors

Moved pipe creation into ConnectionHandler.start() and closes FDs
when zk_loop ends (triggered by stop()).
Fix test for python3
Add client close() method to release pipe FDs

And guard against hitting a closed pipe in _call()
Close clients in testing harness
Merge pull request #55 from python-zk/close_pipe

Fix leak of os.pipe() file descriptors
Update travis-ci links
add link to new mailing list
prepare release
added the changelog for 1.0b1
fix mailing list link
vb
watcher callback invalid only if None
add test for weird watcher
Merge pull request #56 from prezi/watcher-callback-invalid-only-if-none

watcher callback invalid only if None
add changelog entry to #56
choose ports 0, 10, 20, 30... and not 0, 10, 30, 60, ...
Queue with item locking recipe
Added LockingQueue to CHANGES
LockingQueue: fixed tests and documentation
LockingQueue: added test precondition to use ignore ZooKeeper v < 3.4, removed 'ascii'