server: Allow to set the server name.

This actually is just a way of naming your servers in the robot servers
and for personal reference, the name isn't processed any further from
Hetzner.

Thanks to @HolySephi from Hetzner for providing information about this
(and generally big thanks for having the patience to answer my
questions).

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
hetznerctl: Show server name in list command.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
hetznerctl: New subcommand to set server name.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
COPYING: Update copyright years.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Bump version to 0.3.0.

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