[Contributors] Add contributors with >25 PRs

Addresses OAI#1156

Author: RobDolinMS

CONTRIBUTORS.md

@@ -1,7 +1,9 @@
 * Darrel Miller [@darrelmiller](https://github.com/darrelmiller)
 * Jason Harmon [@jharmn](https://github.com/jharmn)
 * Jeremy Whitlock [@whitlockjc](https://github.com/whitlockjc)
+* Kris Hahn [@KrisHahn](https://github.com/krishahn)
 * Marsh Gardiner [@earth2marsh](https://github.com/earth2marsh)
+* Mike Ralphson [@MikeRalphson](https://github.com/mikeralphson)
 * Rob Dolin [@RobDolinMS](https://github.com/robdolinms)
 * Ron Ratovsky [@webron](https://github.com/webron)
 * Tony Tam [@fehguy](https://github.com/fehguy)