Colorized output for supervisorctl status

How about a sexy new feature for 4.0...? :smile: 

I've long wanted this, because it makes the failed processes stand out from the OK ones in a long list.

![supervisorctl_status_colored](https://cloud.githubusercontent.com/assets/305268/5286368/885a5066-7ad8-11e4-8c76-643db94a266d.png)

I'm toying with the idea of colorizing the entire line rather than just the status. Or maybe the name and the status. Having the name colorized seems nice so that your eyes can just scan the first column. Kind of thinking of not colorizing the rest of the line according to status, because I had an idea of maybe colorizing the uptime if it less than a certain threshold (`startsecs`?) -- this is because we sometimes have processes that repeatedly spin up and die and use a lot of CPU, so it can be very useful sometimes to spot the processes that have the shortest uptime...

@mcdonc and @mnaberez: What do you guys think?

I didn't write tests, but I will add them if you're cool with the feature.

I hope that we do not add an external dependency just to get some colored output.  I think a feature of Supervisor is that it has no dependencies besides meld3 (which is our package too), and at some point I'd like to find a way to remove meld3.  Supervisor is widely used by non-Python people and is packaged by a lot of distributions.  Having fewer dependencies makes it easier to install and package for those people.