Add pbos@webrtc.org as owner for webrtc/test/.

BUG=
R=phoglund@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/13839004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6604 4adac7df-926f-26a2-2b94-8c16560cd09d