webadmin botching mutators: found and fixed.

[Ryan C. Gordon]

I found it...pretty straightforward bug.

WebAdmin's passing the index in the list of mutators to the server 
instead of the string, so if xGame.BigHeadMutator was #3 in the list, 
and you select it, it'll do "?mutator=3" instead of 
"?mutator=xGame.BigHeadMutator", which obviously doesn't fly.

Looks like this is in the retail version, too (CRAP!), but we'll put the 
fix in the patch. Fun.

Thanks, admins.

--ryan.