Add tools/sharding_supervisor to .gitignore

I should have thought about this in
http://review.webrtc.org/2314004/

BUG=none
R=niklas.enbom@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/2319004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4870 4adac7df-926f-26a2-2b94-8c16560cd09d
1 file changed