(yoyo) Explanation messages

Fixes #61.

After installing:

![](http://i.imgur.com/buTDGiy.png)

Before running:

![](http://i.imgur.com/cIiAUCV.png)

After updating all generators:

![](http://i.imgur.com/p8MBkmh.png)

Try it out!

Also:

1) I caught a lil' bug. I removed `pkg.namespace` in an earlier refactor apparently, which is pretty important!

2) Not sure `this.env.lookup('*:*');` will work in place of `spawnCommand('yo');`. Anyone know if that will work?