Credit pg: can't change credit role without delete/re-add

Hey.

I noticed you can't change a person's credit role in the current wiki. Adding the person in the proper category and deleting them from unspecified results in an "oops, person already exists" error.

The old system worked way better.

Yeah, I just ran into this problem as well. Pretty annoying.

@wiseblood: Stuff like this makes me feel guilty for not being that active during the beta period. There's a whole bunch of simple usability things that are bugging the crap out of me during my wiki edit routine and the fixes at least seem quite obvious.