Create explicit feature for ScyllaDB

[AlexPikalov]

As we found that CDRS with feature v3 (3-rd version of Apache Cassandra binary protocol) works fine as a driver for ScyllaDB, it would make sense to create an explicit feature scylla-db.

As of now it should behavior as if CDRS has been imported with v3 feature.

[penberg]

@AlexPikalov ScyllaDB also support CQL v4. If you found something that's not working, we'd love to here about. From driver point of view, there should be no difference between Apache Cassandra and ScyllaDB -- if there is it's a bug that we'd like to fix.

[AlexPikalov]

@penberg Ahh... Probably my knowledge about that is a bit outdated. Thank you for pointing on that 😃

[AlexPikalov]

I'll try CDRS with v4 and ScyllaDB and if it would work we could close this issue. Especially if ScyllaDB follows Cassandra protocol without any exceptions.

[penberg]

@AlexPikalov It does (except for bugs).