Check/remove "address books" sync authority & content provider

[rfc2822]

Before using workers for automatic sync, we needed the "address books" sync authority and content provider so that sync intervals could be set for address books. As far as I remember, there was no other purpose.

• Check whether "address books" sync authority and content provider is still needed.
• If not, remove them.

[sunkup]

I think it's actually possible to remove the address books authority and provider. I tried replacing all occurrences with ContactsContract.AUTHORITY and everything still works fine :)

I checked that the following still works:

• Sync Adapter Framework initiated syncs on contact changes
• changing sync intervals to periodic / manual