First step of simplify

This is the first step of #23 and it has a handful of breaking changes:

* Rename `clean` to `cleanup`
* Rename `teardown` to `down`
* Rename `update` to `up`

When this is done, the passengers can step by step be adjusted: Remove the `setup` and `install` methods and adjust the `up` method to do those tasks, too. This can be done one passenger at a time.

When all of them are done, they can be removed from `Ship` and `Spacesuit` and from the Rakefiles.