Add the admin_user api function to the identity helper and the IdentityProvider interface.

modules/gallery/libraries/IdentityProvider.php

@@ -107,6 +107,13 @@ class IdentityProvider_Core {
     return $this->driver->guest();
   }
 
+  /**
+   * @see IdentityProvider_Driver::admin_user.
+   */
+  public function admin_user() {
+    return $this->driver->admin_user();
+  }
+
   /**
    * @see IdentityProvider_Driver::create_user.
    */