docs: Update references to the old repository.

Please note that there are still some references left because I had not enough knowledge whether they should stay or not.
The list of the files remained to be checked are:
Changelog
ci/ci_wheezy.conf
ci/utils.py
contrib/snf-pithos-tools/README
docs/admin-guide.rst
docs/networks.rst
docs/older/README.astakos-app
docs/older/README.pithos-app
docs/older/cyclades-upgrade.rst
docs/quick-install-intgrt-guide.rst
snf-cyclades-gtools/docs/index.rst
snf-deploy/setup.py
snf-deploy/snfdeploy/components.py