* Signaling messages are added to the log with a '+' / '-' sign to expand/collapse the message. This makes the log easier to read and each message can be read separate from the others.
* Loopback enabled by default since that's the most common use case.
* Wrapped some lines at 80 for easier future diffing.
Review URL: http://webrtc-codereview.appspot.com/214001
git-svn-id: http://webrtc.googlecode.com/svn/trunk@711 4adac7df-926f-26a2-2b94-8c16560cd09d
