Fix sudo help and summaries
1) Add sudorule docstring headline
2) Fix naming inconsistency in Sudo plugins help and summaries,
especially capitalization of Sudo objects - Sudo Rule, Sudo
Command and Sudo Command Group
3) Add missing summaries for sudorule-add-option and
sudorule-remove-option. To keep backward compatibility with
older clients, just print the missing summary with
output_for_cli(), don't expand Output.
https://fedorahosted.org/freeipa/ticket/1595
https://fedorahosted.org/freeipa/ticket/1596