Red-Black Tree [Java]

[http://www.geeksforgeeks.org/red-black-tree-set-1-introduction-2/](http://www.geeksforgeeks.org/red-black-tree-set-1-introduction-2/)

The issue only links a GeeksforGeeks red-black tree introduction and does not name a repository file or test. Read the linked article, then inspect the Java algorithm and data-structure layout to find the appropriate entry point. Done should mean a red-black tree implementation is added and fits the repository's existing organization and validation approach.

Written by the indexing model from the issue text.