ZooKeeper 3.6 will add support for Persistent Recursive Watchers - Add Curator support

ZOOKEEPER-1416 will add support for Persistent Recursive Watchers. This feature allows Curator to re-think/re-write the various cache recipes so that they're simpler, use less resources and more stable.

• Change Curator to depend on ZooKeeper 3.6.x
• Add a new module so that backward compatibility with 3.5 is ensured
• Add new methods corresponding to ZooKeeper.addWatch()
• Add a new recipe that enables a fully managed Persistent watch
• Create new Cache recipes that use the new Persistent watch recipe
• Replace internal usages of TreeCache/PathChildrenCache/NodeCache with new cache recipe
• Deprecate TreeCache/PathChildrenCache/NodeCache
• Updated docs/tests/etc