New bugfix release

This is essentially a fix by @rbvermaa, which removes the fields that no
longer exist in the Robot API.

New bugfix release

Only includes a small fix for the login into the Robot Web interface,
which is used to eg. provide access to admin accounts.

New bugfix release

Updates the fallback certificate to the DigiCert Root CA, so that
whenever the probing of the CA bundle fails, the server certificate will
still validate.

New minor release 0.8.0

New features:

 * Support for retrieving reverse PTRs.
 * Support for subnet-ranges.
 * Add logging (#14).

Fixes:

 * Hide internal methods from the public API.
 * Fix Python 3 compatibility.
 * Fix for creating admin accounts with Hetzner's new login site.
 * Fix __repr__/__str__ issue with some exceptions (#23).
 * Fix login for RobotWebInterface

Changes for the hetznerctl utility:

 * show: Show subnets
 * show: Show reverse PTRs
 * New 'rdns' subcommand for getting/setting/removing reverse-PTRs.
 * Use 'argparse' instead of 'optparse'.
 * Add command for managing admin accounts.
 * New '--debug' flag for printing debugging information.

New bugfix release

This fixes an issue reported by @grahamc at:

NixOS/nixops#563

So it copes with the recent changes Hetzner made to their robot and also
provides a more helpful exception instead of just an AssertionError.

New bugfix release.

This fixes the issue reported by @fuzzy-id at:

NixOS/nixops#354

Basically, it updates the pinned certificate and now probes for the
system's CA bundle, so we shouldn't run into that issue again if Hetzner
changes their CA.

The CA that was changed was that of the Robot web interface, not the
API. But I'd expect the API cert to be changing very soon as well.

New bugfix release.

Fixes setting the password of an admin account, because the Robot now
uses a CSRF token.

Thanks to @rbvermaa for reporting the issue and doing extensive testing
of the fix.

New bugfix release.

Fixes the root CA certificate of the Hetzner robot.

Thanks to @Davorak for reporting.

New bugfix release.

This fixes encoding problems for the hetznerctl CLI.

Big thanks to @dangra for the initial fix, pull request (#7) and
testing. Also to @cyberplant for more input and testing.

New minor version.

This release consists of the following changes:

 - hetznerctl: Fix UnicodeEncodeError in server product name.
   (thanks to @haron for the temporary fix)
 - Support rebooting of vServers.
 - Server now has a new attribute is_vserver.
 - Add a README.md with examples.
   (thanks to @zoobab for bringing up the issue)