pep8 1.5 introduced a new test (E265) to ensure there's at least one
space before block comment.

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.

 * 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

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

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

This is needed because otherwise setup.py fails on some systems. Also
do some more cleanup.