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'
LockingQueue: refactoring after code-review
Merge pull request #59 from skd/master

Added a LockingQueue to recipes. When get() method is called this queue locks an item instead of removing it.