All modules should use image_creator.FatalError exception to report
fatal errors.

This is used to prepare the media for image extraction. The main
difference from data_cleanup is that the tasks performed with this
method are mandatory in order to make the image workable.

Added the following sysprep methods for linux:
 * sysprep_acpid
 * sysprep_persistent_net_rules
 * sysprep_persistend_devs

The package is buggy and we can use pbs to do the same thing.

Not workable. Kamaki is not imported yet.

Hooray! This is the first release that actually works!

* Add foreach_file function in OSBase. This is used by all cleanup
  methods
* Add slackware class. This class derives from linux and overwrites the
  log cleanup behaviour. This is needed since slackware stores all
  package management info in /var/log/packages
* Add a shrink method in DiskDevice. This method shrinks the last
  filesystem to the minimum size
* Make the code style comply with pep8