Adding configuration option max_restarts to allow min_update to work properly

Hi! We needed min_update to be a little larger, around 2 seconds, but this didn't play well with pm2 as there was a hard dependency on not failing under 15 seconds. So I fixed that by adding a new configuration property "max_restarts", and modified the code to what I thought was decent. I did add some code in README.md in master only to realize that the one in development was much shorter. And there was no documentation of the JSON format that I could find. How do you want to do with that? Should I make a PR from my master -> master?