Fix dbupdates http request handler

There is no actually handle_req/2 call while case for handling non GET requests
is missed.
diff --git a/src/couch_dbupdates_httpd.erl b/src/couch_dbupdates_httpd.erl
index ec0c4d6..8a7f80f 100644
--- a/src/couch_dbupdates_httpd.erl
+++ b/src/couch_dbupdates_httpd.erl
@@ -37,9 +37,8 @@
 
     State = #state{resp=Resp, feed=Feed},
     couch_dbupdates:handle_dbupdates(fun handle_update/2,
-                                     State, Options).
-
-handle_req(Req, _Db) ->
+                                     State, Options);
+handle_req(Req) ->
     couch_httpd:send_method_not_allowed(Req, "GET").
 
 handle_update(stop, #state{resp=Resp}) ->