Updated the interfaces and dropped oauth version

Seems the oauth lib's stable version is 3.2, dropped down from the 4 version
to that.

src/OAuth2/ScopeStorage.php

@@ -9,7 +9,18 @@ class ScopeStorage extends StorageAdapter implements ScopeInterface
 {
     public function get($scope, $grant_type = null, $client_id = null)
     {
+        $sql     = 'SELECT * FROM oauth_scopes WHERE id = ?;';
+        $results = $this->db->fetch($sql, [$scope]);
 
+        if (count($results) === 0)
+        {
+            return null;
+        }
+
+        return (new ScopeEntity($this->server))->hydrate([
+            'id'          => $result[0]['id'],
+            'description' => $result[0]['description'],
+        ]);
     }
 }