Merge pull request #18 from EricTendian/5.5

Changing logic of isDirty to match with Laravel 5.5 and prevent from always returning false

src/Hookable.php

@@ -144,7 +144,7 @@ public function save(array $options = [])
      */
     public function isDirty($attributes = null)
     {
-        if (! is_array($attributes) && !is_null($attributes)) {
+        if (! is_array($attributes)) {
             $attributes = func_get_args();
         }