Configuration of root keys via databag and attributes

[chris-rock]

The current version uses databags only:
https://github.com/TelekomLabs/chef-ssh-hardening/blob/master/recipes/server.rb#L74-L79

We should support databags and attributes and merge the the keys. Simple flags should enable users to deactivate databag or attributes usage.

Thanks @bkw for reporting this.

[bkw]

Actually, I'm fine with just supporting data bags. The thing that bit me was that the recipe insists on the databag to exist (although it is perfectly fine with an empty data bag).
That's why I always have to do a "mkdir data_bags/users" prior to runnning my chefspec tests.
Wrapping the access to the data bag into a check whether such a data bag exists would be enough for me.

[bkw]

... and I somehow feel that a PR for just that is about to hit an inbox near you very soon. But now for some sleep...

[chris-rock]

fixed with #50