Remove unnecessary test in decide function

* If `defdecision` would specify a test function which is not a
  function or multi-fn it would be ignored.

src/liberator/core.clj

@@ -71,9 +71,8 @@
 (declare handle-exception)
 
 (defn decide [name test then else {:keys [resource request] :as context}]
-  (if (or (fn? test)
-          (instance? clojure.lang.MultiFn test)
-          (contains? resource name))
+  (if (or test
+         (contains? resource name))
     (try
       (let [ftest (or (resource name) test)
             ftest (make-function ftest)