RescueSystem: Get rid of pexpect dependency.

This uses a SSH_ASKPASS helper script in order to inject the password into SSH.
We also need to use os.setsid here, to make sure, SSH won't try to read the
password from the current PTY/TTY.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Split up hetzner into hetzner.{robot,server}.

This should bring better structure into the code and we don't end up with a big
file with a lot of cross-references.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
RescueSystem.shell: Set SSH LogLevel to quiet.

This is to get rid of annoying warnings, such as:

Warning: Permanently added '###' (RSA) to the list of known hosts.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
robot: Remove magic for getting Server instances.

Now, getting a server by its main IP address is done by using
robot.get("1.2.3.4") instead of using list indices.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Bump version number to 0.2.0.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>