* Make isRestore work in the cluster.
This covers sharded collections with default sharding and non-default
sharding.
* always use locally generate revision ids for storing and looking up documents
arangod may report a "lastLogTick" value of "0" when a request to
/_api/replication/logger-state was made before the first WAL write
operation was synced to disk. After the first sync operation, the
"lastLogTick" values were ok then.
Now a "lastLogTick" value of "0" should not be returned even when
the logger state API is queried directly after the startup.