portfolio: MDL-16417 Prevent multiple googledocs/picassa instances

portfolio/googledocs/lib.php

@@ -93,6 +93,9 @@ class portfolio_plugin_googledocs extends portfolio_plugin_push_base {
         google_docs::set_sesskey($this->sessiontoken, $this->get('user')->id);
     }
 
+    public static function allows_multiple_instances() {
+        return false;
+    }
 }
 
 /**

portfolio/picasa/lib.php

@@ -86,6 +86,9 @@ class portfolio_plugin_picasa extends portfolio_plugin_push_base {
         google_picasa::set_sesskey($this->sessionkey, $this->get('user')->id);
     }
 
+    public static function allows_multiple_instances() {
+        return false;
+    }
 }
 
 /**