Making max_workers a configurable parameter in the workload config JSON

[Nalin28]

I used faas-profiler to send traffic to Knative (endpoint: generic) and it only sends in 100 async request invocations even though my workload config JSON has an ideal peak average concurrency of more than 100.

Steps to reproduce:

Use the workload_configs_generic_endpoint.json under faas-profiler and specify your host and URL (I used it with interarrivals_list with average peak concurrency > 100).
run $ ./WorkloadInvoker -c workload_configs_generic_endpoint.json

Fix

Pass the field in the JSON as max_worker and propagate it through the WorkloadInvoker instead of hardcoding it.

[engshahrad]

#32 also resolves this.