- 2 new packages (image and repository).
- Split big modules into little one under packages.
- Replace full module import by needed objects
- Avoid wildcard imports
- Fix a lot of pylint error and warnings on modules

Old repository are still usable.
Database changes:
Add is_min_version and image_format in image table.
Add repository table which contain database uuid, version and motd.

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

ISException is an Installsystems exception which can handle an exception and
his information (type, value, traceback).

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)

this option allow list of image without syncing database. Very useful for completion

currently db badly create if directory already exists before creation

This also change underlying way of initiliaze a repository.
A repository can now be defined and be innaccessible

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

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

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

We stop using bzip2, because implemetnation of python 2.7 bz2 is uncompatible
with pbzip2. So tarball created with pbzip2 cannot be uncompressed with python.
So we need to find a speedy and portable compression algorithm. Gzip is the
best candidate

Now use databases function to delete files from repository