[Unreal] Work out a good way to set the network version

[markmandel]

Right now we are just doing:

		FNetworkVersion::IsNetworkCompatibleOverride.BindLambda([](uint32 LocalNetworkVersion, uint32 RemoteNetworkVersion)
		{
			return true;
		});

Since our client and server builds are on different machines and different Unreal engine installations, and it's messy.

We should come up with a better way of matching clients to servers -- maybe by git hash?