Author: Ram Sriharsha <rsriharsha@hw11853.local>

Closes #6443 from harsha2010/SPARK-6013 and squashes the following commits:

732506e [Ram Sriharsha] Code Review Feedback
121c211 [Ram Sriharsha] python style fix
5f9b8c3 [Ram Sriharsha] python style fixes
925ca86 [Ram Sriharsha] Simple Params Example
8b372b1 [Ram Sriharsha] GBT Example
965ec14 [Ram Sriharsha] Random Forest Example

(cherry picked from commit dbf8ff38)
Signed-off-by: Joseph K. Bradley <joseph@databricks.com>