Contacts: Google Contacts sync

[flack]

Reported by bergie on 9 Jan 1959 19:25 UTC Quite a lot of companies are using Google Apps for Enterprise. Synchronizing with Google Contacts would make OpenPSA sit better in that environment.

There are two sync APIs available:

* Read-only: http://code.google.com/apis/contacts/docs/poco/1.0/developers_guide.html
* Read-and-write: http://code.google.com/apis/contacts/docs/3.0/developers_guide.html 

Migrated-From: http://trac.openpsa2.org/ticket/19