Increment ports for concurrent procs

[rwc9u]

What does it do?

• Adds procNum to the port calculation for startProc
• Adds TestStartProc

What else do you need to know?

• The current implementation maintains the same port when concurrency is added. This change increments the port count by 1 similar to the original foreman and node foreman.

Example

Procfile

web: node app.js

-bash  ~/dev/helloexpress  ⬙ 2.5.3p105  ⬢ system
rchristie@greed    ~/go/src/forego/forego start -c web=2
forego | starting web.1 on port 5000
forego | starting web.2 on port 5001
web.2  | Example app listening at http://localhost:5001
web.1  | Example app listening at http://localhost:5000
^C      | ctrl-c detected
forego | sending SIGTERM to web.1
forego | sending SIGTERM to web.2

[bugficks]

@rwc9u
Thanks, merged.