build -p recreate payload file if already exsits

is build now create payloads without version in name and create symplink with version to it.

This is very useful to avoid too many recreation of payload after adding to db or when bumping version

* tricks /etc/mtab
* new output

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

is list command now only list image inside repositories.
many option can be given to have a custom output
globbing is allowed on images

all options have now a long mode
some options name have changed

This command allow a clean listing of repositories

When we create gzip file from a payload, we use gzip module with option mtime
which is not available in python 2.6.
To be able to support it correctly, i've backported python 2.6.7 gzip
module inside installsystems with a patch allowing optime mtime.

This should be removed with python 2.7 or 3.x

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

this already more easy unchrooting after failure by chrooting again,
solving issue and exiting (which remove mounts again)

compute of real path of images to check integrety was poorly coded. Fix it!

chroot failed when root is missing dirs before resolv.conf fil

This is done to be able to use preparation from scripts

new option --preserve, -p is added

completion and is add -p <tab> doesnt work because cword is used and doesn't escape options from the list