Add alternative way to supply username/password to CassandraClientOptions

[Deleted user]

Adding the possibility to add username/password to the options might make the API a bit easier (opinion). I wouldn't mind to work on the implementation if agreed upon.

Current solution looks something like this:

    val options = CassandraClientOptions()
      .dataStaxClusterBuilder().withCredentials(
        settings.getString("cassandra.username"),
        settings.getString("cassandra.password")
      )

    val client = cassandra = CassandraClient.createShared(vertx, CassandraClientOptions(options))

While we maybe want to do something like this:

    val options = CassandraClientOptions(options)
        .setUsername("username")
        .setPassword("password")
    val client = cassandra = CassandraClient.createShared(vertx, options)

[tsegismont]

Closing this one as a duplicate of #31