Regression fix: rule table with ext. member support doesn't offer any items

There is a JS error.

Rule tables with external member has more than one column and therefore exclude parameter for adder dialog is not array of strings but array of objects. normalize_values function can't work with it and causes JS error.

This patch creates proper exclude array before passing it to adder dialog.

https://fedorahosted.org/freeipa/ticket/3711
Fix displaying of success message

Make sure that the success message is properly populated with actual number of
items that were successfully added/removed.

https://fedorahosted.org/freeipa/ticket/3708