This combination causes iOS to keep trying to bring up the tunnel,
leading to a lot of displayMessage() alerts.
In this fix, if we get a DNS resolution error in an Activate On Demand
enabled tunnel, we silently retry 9 times (with a 4-second delay before
each retry) and then show the displayMessage() alert.
The VPN-on-demand settings should not be part of the tunnel
configuration. Rather, the onDemandRules stored in the
tunnel provider configuration serve as the one place
where the VPN-on-demand settings are stored.
We make sure existing tunnel serializations can be deserialized correctly.
We also bump up the tunnelConfigurationVersion, because the tunnel
configuration contents have changed.
Jason A. Donenfeld
Eric Kuck
Roopesh Chander