Traverser DFS/BFS pre/post order examples in Kotlin

There few things which would be nice to have as part of this PR:
- example of how to import Traverser into Kotlin project
- sample code snippet which runs DFS/BFS pre/post order against example data set (for example company organization chart or bring your sample)

As one of practical suggestion -- StackOverflow or some other forum might have a question about traversing something in mobile app, this could be a good tasks which can be solved with traversal as well.

This task specify #16 for @qbool