feat(recipe): Add TreeCache recipe

Kazoo implementation of Apache Curator's TreeCache recipe. See also:
http://curator.apache.org/curator-recipes/tree-cache.html

Author: tonyseek

docs/api.rst

@@ -16,6 +16,7 @@ organized alphabetically by module name.
    api/interfaces
    api/protocol/states
    api/recipe/barrier
+   api/recipe/cache
    api/recipe/counter
    api/recipe/election
    api/recipe/lease

docs/api/recipe/cache.rst

@@ -0,0 +1,26 @@
+.. _cache_module:
+
+:mod:`kazoo.recipe.cache`
+----------------------------
+
+.. automodule:: kazoo.recipe.cache
+
+Public API
+++++++++++
+
+    .. autoclass:: TreeCache
+
+        .. automethod:: start
+        .. automethod:: close
+        .. automethod:: listen
+        .. automethod:: listen_fault
+        .. automethod:: get_data
+        .. automethod:: get_children
+
+    .. autoclass:: TreeEvent
+        :members:
+        :show-inheritance:
+
+    .. autoclass:: NodeData
+        :members:
+        :show-inheritance: