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

New module tools offer functions to base is class and also to setup scripts.
Drop RepositoryBase class.