add stress-test use case

[kamilsk]

octopot/forma#47

semaphore create 2
semaphore add -- curl -O http://user:pass@localhost:8080/debug/
semaphore add -- hey -cpu=2 localhost:8080/api/v1/{schema}
semaphore wait

extend this: provide a profile to https://github.com/google/pprof

[kamilsk]

https://github.com/loov/hrtime