Bug 1041393 - alert notification of type Resource operations is not
correctly rendered by API

AlertNotificationRest extended with extraConfig field where we now output
notification extra config (in case of Resource Operations alert sender, it's
input parameters for operation)

With this commit we now also properly render alert notification config
(simple property types mapped correctly to JSON/XML, not "just" string
values)

This commit fixes ConfigurationHelper#configurationToMap which transforms
Configuration to generic Map, now it can work without Configuration
Definition
- as a fall-back it maps all simple properties to string values.