PolicyCenter support for creating external unique IDs

PolicyCenter provides support for creating external unique IDs with the following:

• The Contact entity in PolicyCenter is extended with the field ExternalID, which stores the value of the unique ID that PolicyCenter generates.
• The ContactMapper class in PolicyCenter has field mapping definitions for various EXTERNAL_UNIQUE_ID fields. Those definitions are described in PolicyCenter mapping of externally specified unique IDs.
• PolicyCenter has code that generates a new unique ID and assigns it to the ExternalID field of a new contact. PolicyCenter then calls the ABContactAPI.createContact method, passing it the data for that new contact. See the class gw.api.contact.PCContactLifecycle.
• PolicyCenter has an EventFired rule that responds to a ContactAdded event and sends a newly created contact to BillingCenter.