Allow reserving a nickname when adding new room member in Admin Console

Please extend the functionality to the new 3.0 ad-hoc commands, not just in the admin console.

Removing the 'fix version' for all unresolved issues that were scheduled for version 7.8.2. We're releasing this version today - the remaining issues should be rescheduled later.

Apologies for my poor grammar in the original title.

I propose renaming the title to "Allow reserving a nickname when adding new room member in Admin Console".

And change the description to "In muc-room-affiliations.jsp, when adding a new member we should let admin to reserve a nickname for this room member. If nothing was defined and the JID belongs to a local user then set the name of the user as the nickname of the member."

In current PR it sets nickname to a username, if nothing is defined. If this behavior is final, then replace name with username in the description.

I've applied the suggested modifications.