Add monitor mode

I add just add a monitor mode, like an in-place watch.

> -m --monitor            loop while monitored processes are still running
> -M --monitor-continous  like monitor but never stop (similar to watch cv)

I just place most of your main code in a function monitor_processes() and just place a do while() around the call.

![screen shot 2014-07-16 at 18 18 36](https://cloud.githubusercontent.com/assets/363342/3602551/53115672-0d0d-11e4-9028-daf4b6b41eb1.png)