build-debian-cloud python version preview

[Anders Ingemann <anders@ingemann.de>]

Hi everybody

The first preview release of my python version of the
build-debian-cloud bootstrapper is ready and available at
https://github.com/andsens/build-debian-cloud/tree/python
I would welcome any suggestions for improvement.
Keep in mind that this is not a stable release, a lot of polishing is
needed before that can happen.

Some of the features are:

* The desired image is configured entirely via a JSON manifest file
  * Manifests are validated by a json schemas
  * Support comments
* Proper support for different providers
* The task based system has been completely revamped
  * Higher granularity increases reusability of tasks across providers
  * Tasks are neatly organized into modules
  * A task dependency graph is built to determine the execution order
* Support for rollback actions if something fails
* Logfiles
* All output from invoked subprocesses is logged

This is version actually works (!), you can bootstrap an image by running
./build-debian-cloud manifests/ec2-ebs-pvm.manifest.json

Anders