Fix authorized keys

The module autorized_keys didn't work when I tried with the new key_options parameters.
First, the line created was using space as separator, not commas. Then, fixing this one, i found out that finishing the option with a single comma confused the options parser. Finally, for reproducibility and to avoid trigger tools like AIDE, it would be better to have a consistent order of option, since the module rewrite completely the file each time.