Python rewrite

Hi, here is the Python-rewrite of the debops-scripts.

Notable changed related to the shell-version:
* Playbooks are no longer searched in `/usr/local/share/debops` nor in
  `/usr/share/debops`. We assume DebOps is used from a user account,
  so installing playbooks globally is not the common case.

* Sourcing `.debops.cfg` is no longer supported, `.debops.cfg` now is
  assumed to be an ini-file.

* The `ansible_config_hook` (which was undocumented anyway) is gone.
  Instead you can put sections `[ansible ...]` into `.debops.cfg`
  which will go into `ansible.cfg`. This allows for easy adding e.g. a
  `[paramiko]` section to `ansible.cfg`.

* The padlock-script is no longer used to decide if secrets are
  encrypted. This is now done by testing for the encrypted keyfile and
  the encrypted encfs-config.

* The padlock script still exists and has been simplified a lot. Most
  functionality has been moved into the DebOps python library.