Fix race condition by relying on admin only

Since we no longer have to worry about filtering for users we can let
fabric take care of the underlying limit implementation for now. Without
this there's a race condition where fabric will wait for Timeout seconds
before actually stopping. Any activity in that window will be sent
through the callback and forwarded on to clients. There's probably a way
to fix that but my brain isn't working so well right now.

src/global_changes_httpd.erl

@@ -39,7 +39,8 @@ handle_global_changes_req(#httpd{method='GET'}=Req) ->
     % Limit is handled in the changes callback, since the limit count needs to
     % only account for changes which happen after the filter.
     Limit = couch_util:get_value(limit, Options),
-    Options1 = lists:keydelete(limit, 1, Options),
+    %Options1 = lists:keydelete(limit, 1, Options),
+    Options1 = Options,
     chttpd:verify_is_server_admin(Req),
     Acc = #acc{
         username=admin,