CURATOR-145: TreeCache should implement maxDepth
Clarify TreeCache.Builder.setMaxDepth() doc.
Add a deeper TreeCache test with maxDepth.
Merge branch 'CURATOR-145'

* CURATOR-145:
  Add a deeper TreeCache test with maxDepth.
  Clarify TreeCache.Builder.setMaxDepth() doc.
  CURATOR-145: TreeCache should implement maxDepth