Fixes issue 555 by replacing the bitrate/observer map with a list.

The issue was caused by the fact that the key of the map was an address and
therefore the order of the map wasn't deterministic, which the tests assumed.

BUG=555

Review URL: https://webrtc-codereview.appspot.com/735006

git-svn-id: http://webrtc.googlecode.com/svn/trunk@2602 4adac7df-926f-26a2-2b94-8c16560cd09d
3 files changed