Improve CLI output for complex commands
    
    Complex commands may have many options or non-standard output. This
    patch adds 2 improvements to handle these commands better:
      1) Add "option_group" parameter attribute
         Make command help more readable by specifying an option group
         for the parameter. All parameters in the same option group are
         then placed to one named option group
      2) Allow nested entries in the output
         Current CLI output module cannot handle a list of nested entries
         (dictionaries) contained in an entry attribute. Make sure they
         are printed properly (with indentation)
    
    https://fedorahosted.org/freeipa/ticket/2082