Allow to only create applied_migrations table as Pillar 3.3.0 does.

[manuelkiessling]

I'm going to send a PR for this.

[magro]

Sounds good! :-)

[manuelkiessling]

Yes, but of course there is a hook attached :-)

Please see Galeria-Kaufhof@d7172c3

This doesn't compile because ReplicationOptions is history in Pillar 3.3.0. Getting to the correct ReplicationStrategy is much more involved now, and it seems like we'd have to extend sbt-pillar-plugin's config scheme in order to honor complex NetworkTopologyStrategy configs.

Do you see a simple solution?

[magro]

So the question is how to allow the user to configure the ReplicationStrategy? I'd go for s.th. like what com.datastax.driver.core.ReplicationStrategy#create or com.datastax.driver.core.KeyspaceMetadata#build does. E.g. the user could specify

cassandra.replicationStrategy = "'class' : 'NetworkTopologyStrategy', 'dc1' : 3, 'dc2' : 2"

or

cassandra.replicationStrategy = "'class' : 'SimpleStrategy', 'replication_factor' : 3"

This should be fairly intuitive as it's quite close to the CQL documentation.

We could still keep support for cassandra.replicationFactor to override / set the replication factor if needed.

WDYT?