WebChannel ios client testing - networking failures

Two scenarios

1. Turn off wifi and mobile data
2. Switch between wifi and mobile data
3. Silent drop

For 1), with the default v8 wire config, webchannel should be aborted in 30s from the client side.

For 2), webchannel should continue working but we need to check how long forward channel and back channel may be stuck following the handoff.

For 3), the idea is that SCNetworkReachability will stay ON but packets are dropped. In such a case, webchannel will abort after a much longer period esp. without client-sent messages (forwarchannel).