Remove the buggy conversion of metadata to strings

 * Add text/plain as content type in the md5sum file
 * Add application/json as content type in the meta file

Allow the user to upload the image to a different container than the
"images" one.

Allow the user to change the destination container when uploading
images.

Otherwise kamaki complains

Support kamaki 0.13rc5. From this version on, kamaki uses ssl
certificates by default. For now, instruct kamaki to ignore the
certificates.

According to the decision of the GRNET Board of Directors,
switch license to GPLv3.

This commit will be propagated to the release
and master branches based on git flow, and the next
release will be licensed as GPLv3.

Allow the characters that kamaki allows

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

 * 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.

In kamaki 0.8 `store' command is replaced with `file' and `astakos' is
replaced with `user'.

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.

It has changed after the last major revision and was not updated.

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.

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

Otherwise the registration may fail.

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 progress bar of the progress generator had a wrong max attribute.

All image-creator components now output messages using an instance
of one of the output classes.

Also rearrange input options

This is just a template. Not fully workable

Also merge data_cleanup tasks with syspreps and did a major cleanup