Add codereview.settings to the /webrtc subdirectory

With this, it will be possible to create CLs from
Git repos created using
https://chromium.googlesource.com/external/webrtc/trunk/webrtc

TBR=niklas.enbom@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/29169004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7818 4adac7df-926f-26a2-2b94-8c16560cd09d