The meaning of "Cylons should have a model" was very unclear to me, especially since you wanted the "model" to be string or an arbitrary number (I expect a model to be a data object).

Here's another way we could setup this kata

A Cylon can be created as either a raider, a basestar, or a centurion. 
Each type of Cylon has a different attack strategy...

so that depending on what argument you pass the Cylon, the return value of of Cyclon#attack would change. Maybe it could be something like Destroy all humans using [attack strategy].

You could do something similar HumanSkin.

But map is 4 characters shorter than forEach!

Use arr.map if you want to change the values of the array. For regular iterations through array values, you can use arr.forEach

FYI: Array.prototype.forEach accepts a context object as a second argument. So instead of

var self = this;
arr.forEach(function() { 
  self.whaveter(); 
}

you can simply do:

arr.forEach(function() {
  this.whatever();
}, this);

It sure is concise, but it fails the "I know immediately what this code does" test.