More config info during startup

Right now we are logging a bunch of info about configuration when the server starts up. But we are not logging the following info:

1. If JWT is configured or not, what is the JWT configuration (from @0x777)
2. Subscription configurations

Better logging of startup time

We are logging the startup time as a part of startup message:

{
  "timestamp": "2019-05-13T15:00:01.491+0530",
  "level": "info",
  "type": "startup",
  "detail": {
    "kind": "server",
    "info": "starting API server, took 9.0910022e-2s"
  }
}

Maybe we should log the startup time in another variable called time_taken or something like that ?