Make snf-image-creator be the dialog-based program and snf-mkimage be
the command line one.

This can be used to perform various tests to determine if the media
is supported.

Add a new "Unsupported" os_type class. Images that get created from
unsupported media have the EXCLUDE_ALL_TASKS property enabled.

--print-sysprep should be --print-syspreps

The user may define parameters needed by the os_type classes to perform
the system preparation tasks.

A new needed_sysprep_params method is added to os_type.OSBase that
returns a list with parameters that should be defined by the user.

In the documentation and the printed messages, remove all references
to ~okeanos, pithos or cyclades.

When registring an image, use the information returned by the
kamaki register method to construct the metadata file.

When dumping the image to the local filesystem, store the image
properties and the disk-format info in the metadata file.

This options can be used to get the authentication URL and token
from a saved cloud section in the kamaki configuration file

 * Change the authentication everywhere to use clouds
   (authentication URL and token pairs)
 * Add menu entries to manage clouds
 * Add an extra -a option in snf-image-creator to allow the user to
   specify authentication URLs

 * Prefix all private methods with _
 * Write missing docstrings
 * Move all public methods above the private ones
 * Add module docstrings where missing
 * Define source code encodings on all modules

If the image gets registered as public allow anyone to read the
metadata and the md5sum file.

Before uploading to pithos, check if any remote file gets
overwritten.

Check if the filesystem is mounted read-write before you execute
the do_sysprep function

Rename DiskDevice class to Image and move it to a seperate module.
Also, don't let the user access the os_type/* modules directly. In
Image class create the `os' member variable that will host an
appropriate instance of one of the OSBase classes.

Support images that can only be deployed by the user that registers
the image to cyclades

You don't need the account name. You can fetch it from astakos using
the authentication token.

The cow file when creating images or the temporary image file when
bundling the host system may be large. Allow the user to overwrite
the directory under which those files get created.

This reverts commit 883e57b0.
Drop the greenlet support.

Needed by new kamaki, otherwise it throughs an exception at the end.

Fix various typos in messages, add .gitignore file for
automatically produced intermediate files.

Fixed many `E127 continuation line over-indented for visual indent'
errors

This method returns a sysprep object with a given name. Now,
(enable,disable)_sysprep work with sysprep objects instead of sysprep
names

If no customization is to be applied the image should be mounted
readonly.

Let the application decide what to do with them. If image-creator
receives an error from kamaki it will terminate. But this may not be
the proper thing to do for an interactive application like
image-creator-dialog

The error function main.py used for outputing errors has been removed
and the code was not updated to use the error method of SimpleOutput
output class.
Also did a minor cleanup: git_os_class function was renamed to os_cls