Add json:omitempty tag to webrtc.Configuration
Add json:omitempty tag to webrtc.Configuration

The peerIdentity field can be null, in which case the peer identity
is not checked.  We used to send the empty string in that case, which
happens to work with common browsers but is probably incorrect.

pion/webrtc,pion/webrtc,pion/webrtc,pion/webrtc