Add performance workout to node course

[lizTheDeveloper]

Create a workout that covers the following objective:

• Use profiling tools to discover and resolve server latency issues

Resources: https://github.com/nearform/node-clinic https://github.com/sidorares/node-wrk https://github.com/mcollina/autocannon

This workout should come with a glitch.com programming environment that is set up to be profiled, with some issues that can be resolved and discovered by the profiler. Here's an example app that could be profiled (though you may need to create some problems.)