We now use system tar and gzip to compress/decompress payloads

Goals are:
- Speed-up extraction and creation of payloads.
- Allow to use non-python supported compressor like (pbzip2 and xz)
- Remove python2.7.1 tarfile.py module
- Remove python 2.7.1 gzip.py to avoid filename to be in gzip headers
- Remove gzipstream.py module used to stream gzip file

this options are also settable by config
allow to have installsystems niced before launch action

python-psutil minimun version is 0.2.1 to support set_ionice

we need python-progressbar >= 2.3 to work with is.
We previously ship inside it because debian doesn't have 2.3 package available.
now we have built a debian package, we can remove code and add a dependency

python-argparse (1.1) shipped with debian squeeze is bugged and doesn't work with installsystems needs
python-argparse 1.2.1 (last upstream version) was backported into squeeze and we need it.

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

We need installsystems is functional on squeeze systems...

So we needs to embed:
- argparse 2.7.1 (not in python2.6)
- progressbar 2.3 (not in debian squeeze)

This commit introduce remote repository and file accross ssh

We now use PipeFile to handle complex file type and compute md5 and filesize.

This commit add the following features in installsystems:
- A download progress bad
- check size before download
- check size after download
- check md5 after download

This will help remi to be cool and save some day in his life