Compressors are specified in description file.
For example:

[compressor]
gzip = *
none = *.gz, *.bz2
bzip2 = rootfs*

This description file set gzip as default compressor, do not compress payload
which end with .gz and .bz2 and use bzip2 as compressor for payload matching
'rootfs*'

Signed-off-by: Sébastien Luttringer <sebastien.luttringer@smartjog.com>

Image version now accept a string of digit separated by dots and extra char as
a qualifier (~ or +).

Example:
1.2.3.4~dev < 1.2.3.4 < 1.2.3.4+dev

Old repositories are still compatible thanks to sqlite type affinity
(https://www.sqlite.org/faq.html#q3

).

We use a package version comparison algorithm for image version comparison
inspired by Debian.

Seblu: Fix typos

Signed-off-by: Sébastien Luttringer <sebastien.luttringer@smartjog.com>

With the permission of Romain Degez, CTO of Smartjog and Sébastien Luttringer.

Signed-off-by: Sébastien Luttringer <sebastien.luttringer@smartjog.com>

If we have to format (aka interpolatation) we need to be sure this have to be
done in unicode and not in ascii. This avoid unicode error with ascii string
encoded in utf-8.

Example of failure between a string and an object

b = Exception(u"é")
Exception("error: %s" % b)
 => Exception("error: %s" % str(b)
 => UnicodeEncodeError: 'ascii' codec can't encode character u'\xe9' in position 0: ordinal not in range(128)

argparse is available in python2.7 (archlinux) and on python-argparse package in debian. So
we add a dependency to this package.

we can now set a minimal installsystems version in your description
install will not be able to read those images

Signed-off-by: Sebastien Luttringer <sebastien.luttringer@smartjog.com>

tarfile module fail to extract tarball with utf8 filenames when destination is an unicode
string. We need to convert dest as utf-8 string to restore an expected behaviour

Add a changelog file inside isimage with a custom format which allow
image creator to quickly show update between images

Arrow is now relative this allow to pass context of arrow
no more verbose mode. Soft is verbose except in quiet mode

Script is now compiled before execution to have a better debugging features.
local directory is no more given for each scripts
global directory is new to each script execution
only namespace object must be used to share data across scripts

Concept of data was changed to payload.
Payload is not necessary a tarball of a file or a directory, but, directly a file without tarball around.
This is useful have the same md5 on data/payload and win some space during repo adding.
Now data which come with image are represented by class Payload and all operation are located inside. This is cleaner!
Payload also handle orginial information (mtime,uid,gid,md5,size,mode)

This changement require a lot of changement in Repository and RepositoryManager class

This commit change a lot of things in installsystems way of life.
Repository cache is now disabled on access to remote repository done directly.
New database and tarball format