mongo-sync: store/load operations perform deep copy on the cache object

Signed-off-by: Budai Laszlo <lbudai@balabit.hu>
mongo-sync: recovery_cache_seed_add() supports unix domain sockets

Signed-off-by: Budai Laszlo <lbudai@balabit.hu>
Merge pull request #29 from lbudai/f/failover_refact

mongo-sync: store/load operations perform deep copy on the cache object