[iOS] Get address book thumbnail if the method is available. Should weakly link the framework.

AddressBookImage.m

ABAddressBookRef addressBook = ABAddressBookCreate();
NSArray *allAddressBookPeople = (NSArray *)ABAddressBookCopyArrayOfAllPeople(addressBook);
for (int i = 0; i < [allAddressBookPeople count]; ++i) {
	ABRecordRef record = [allAddressBookPeople objectAtIndex:i];
        NSData *imageData = nil;
        if (ABPersonCopyImageDataWithFormat != NULL) {
                imageData = (NSData *)ABPersonCopyImageDataWithFormat(record, kABPersonImageFormatThumbnail);
        } else {
                imageData = (NSData *)ABPersonCopyImageData(record);
        }
}