Configuration of replication strategy parsing fix.

[npatsakula]

The class property obviously can't be parsed by extract_replication_factor. I fixed parsing, but it's still not type safe, maybe I make a few MR later.

[krojew]

To confirm - the actual problem is with extract_datacenter_replication_factor iterating over properties, not extract_replication_factor?

[npatsakula]

To confirm - the actual problem is with extract_datacenter_replication_factor iterating over properties, not extract_replication_factor?

extract_datacenter_replication_factor assumes, that properties contains only replication properties, but it's incorrect (build_replication_strategy didn't remove class property and it's still in the map).