Finish all demo plots

I have finished the code for demo plots.

The three includes:
1. round robin routing
2. two routers: one 'rr' and one 'rand'
3. instance failure. If both routers reported failure, controller will remove that from both routers.

I tested it on my local machine so there is a hack:
'rand' has service 'test service' on port 8080
'rr' has service 'test service' on port 8081

In demo, both will become 8080 on some remote machines.

What's left to be done:
We just need to host some other machine (VM, docker) with IP to demo and record the show.