Add missing sections

Add a part explaining the usage and input options of the
non-interactive version of snf-image-creator.

Add SORTORDER image property

Also add a basic readme file.

Create a new dialog_menu module to host all the "expert mode" code.
Check the code with a new version of pep8

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

Every time you tried to reupload an image, the dialog displayed the
pithos url instead of the image filename as initial value.

Extend the mechanism to recognise events with value "button/power.*"
as power button events. It used to only check for events with value
"button[ /]power".

The function used to ignore directories when cleaning sensitive data

The account info was saved in the token field in .kamakirc

The size of the cow file was hardcoded to 1G. This was buggy, because
for a big image, the resize operation could fill up the cow file and
fail.

Fix some typos and overwrite the yes/no labels of the wizard/expert
mode yesno dialog

Also move it to a separate module.

Logging can be enabled using the -l input option

After the image has been uploaded to pithos and registered to cyclades,
prompt the user about saving the uploaded image locally.

This exception can be used by the WizardPage instances to exit the
wizard.

Make the ImageDescription field of the dialog wizard overwrite the
DESCRIPTION image property.

In the cli output classes this method will clear terminal screen if
the standard output is a terminal.

If snf-image-creator does not find any passworded user, then the
USERS metadata field is not created at all.

A user can now create and upload an image using the wizard

The system does not perform anything yet when in wizard mode.

Create the new python module to host the aforementioned code.

If present in the kamaki configuration file, the user will read
the ~okeanos credentials using the kamaki config interface.
Whenever the user changes the ~okeanos credentians, the changes are
pushed back to kamaki.

Not fully implemented yet

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

Before extracting an image or registring it with cyclades, the image
properties are populated with metadata concerning excluded deployment
tasks.

Most partition manipulation programs leave 2048 sector empty space
after the last partition.

The method used a wrong warning output function