Remove dispensable logic in the IQOwnerHandler, which deals with MUC affiliation changes

MUC affiliations are managed in the #admin namespace, not in the #owner namespace.
This is already a minor contribution to OF-178 (Updating MUC to latest version).
Merge pull request #42 from sco0ter/of178

Remove dispensable logic in the IQOwnerHandler, which deals with MUC aff...